OpenAPI Specification v3.1.1

What is the OpenAPI Specification?

The OpenAPI Specification (OAS) defines a standard, programming language-agnostic interface description for HTTP APIs, which allows both humans and computers to discover and understand the capabilities of a service without requiring access to source code, additional documentation, or inspection of network traffic. When properly defined via OpenAPI, a consumer can understand and interact with the remote service with a minimal amount of implementation logic. Similar to what interface descriptions have done for lower-level programming, the OpenAPI Specification removes guesswork in calling a service.

The OpenAPI Specification is versioned using a major.minor.patch versioning scheme. The major.minor portion of the version string (for example 3.1) SHALL designate the OAS feature set. .patch versions address errors in, or provide clarifications to, this document, not the feature set. Tooling which supports OAS 3.1 SHOULD be compatible with all OAS 3.1.* versions. The patch version SHOULD NOT be considered by tooling, making no distinction between 3.1.0 and 3.1.1 for example.

Occasionally, non-backwards compatible changes may be made in minor versions of the OAS where impact is believed to be low relative to the benefit provided.

An OpenAPI Document that conforms to the OpenAPI Specification is itself a JSON object, which may be represented either in JSON or YAML format.

For example, if a field has an array value, the JSON array representation will be used:

{
  "field": [1, 2, 3]
}

All field names in the specification are case sensitive. This includes all fields that are used as keys in a map, except where explicitly noted that keys are case insensitive.

The schema exposes two types of fields: fixed fields, which have a declared name, and patterned fields, which have a declared pattern for the field name.

Patterned fields MUST have unique names within the containing object.

In order to preserve the ability to round-trip between YAML and JSON formats, YAML version 1.2 is RECOMMENDED along with some additional constraints:

Tags MUST be limited to those allowed by YAML’s JSON schema ruleset, which defines a subset of the YAML syntax and is unrelated to JSON Schema.
Keys used in YAML maps MUST be limited to a scalar string, as defined by the YAML Failsafe schema ruleset.

Note: While APIs may be described by OpenAPI Descriptions in either YAML or JSON format, the API request and response bodies and other content are not required to be JSON or YAML.

An OpenAPI Description (OAD) MAY be made up of a single JSON or YAML document or be divided into multiple, connected parts at the discretion of the author. In the latter case, Reference Object, Path Item Object and Schema Object $ref fields, as well as the Link Object operationRef field, and the URI form of the Discriminator Object mapping field, are used to identify the referenced elements.

In a multi-document OAD, the document containing the OpenAPI Object where parsing begins is known as that OAD’s entry document.

It is RECOMMENDED that the entry document of an OAD be named: openapi.json or openapi.yaml.

In order to properly handle Schema Objects, OAS 3.1 inherits the parsing requirements of JSON Schema Specification Draft 2020-12, with appropriate modifications regarding base URIs as specified in Relative References In URIs.

This includes a requirement to parse complete documents before deeming a Schema Object reference to be unresolvable, in order to detect keywords that might provide the reference target or impact the determination of the appropriate base URI.

Implementations MAY support complete-document parsing in any of the following ways:

Detecting OpenAPI or JSON Schema documents using media types
Detecting OpenAPI documents through the root openapi field
Detecting JSON Schema documents through detecting keywords or otherwise successfully parsing the document in accordance with the JSON Schema specification
Detecting a document containing a referenceable Object at its root based on the expected type of the reference
Allowing users to configure the type of documents that might be loaded due to a reference to a non-root Object

Implementations that parse referenced fragments of OpenAPI content without regard for the content of the rest of the containing document will miss keywords that change the meaning and behavior of the reference target. In particular, failing to take into account keywords that change the base URI introduces security risks by causing references to resolve to unintended URIs, with unpredictable results. While some implementations support this sort of parsing due to the requirements of past versions of this specification, in version 3.1, the result of parsing fragments in isolation is undefined and likely to contradict the requirements of this specification.

While it is possible to structure certain OpenAPI Descriptions to ensure that they will behave correctly when references are parsed as isolated fragments, depending on this is NOT RECOMMENDED. This specification does not explicitly enumerate the conditions under which such behavior is safe and provides no guarantee for continued safety in any future versions of the OAS.

A special case of parsing fragments of OAS content would be if such fragments are embedded in another format, referred to as an embedding format with respect to the OAS. Note that the OAS itself is an embedding format with respect to JSON Schema, which is embedded as Schema Objects. It is the responsibility of an embedding format to define how to parse embedded content, and OAS implementations that do not document support for an embedding format cannot be expected to parse embedded OAS content correctly.

JSON or YAML objects within an OAD are interpreted as specific Objects (such as Operation Objects, Response Objects, Reference Objects, etc.) based on their context. Depending on how references are arranged, a given JSON or YAML object can be interpreted in multiple different contexts:

As the root object of the entry document, which is always interpreted as an OpenAPI Object
As the Object type implied by its parent Object within the document
As a reference target, with the Object type matching the reference source’s context

If the same JSON/YAML object is parsed multiple times and the respective contexts require it to be parsed as different Object types, the resulting behavior is implementation defined, and MAY be treated as an error if detected. An example would be referencing an empty Schema Object under #/components/schemas where a Path Item Object is expected, as an empty object is valid for both types. For maximum interoperability, it is RECOMMENDED that OpenAPI Description authors avoid such scenarios.

Several features of this specification require resolution of non-URI-based connections to some other part of the OpenAPI Description (OAD).

These connections are unambiguously resolved in single-document OADs, but the resolution process in multi-document OADs is implementation-defined, within the constraints described in this section. In some cases, an unambiguous URI-based alternative is available, and OAD authors are RECOMMENDED to always use the alternative:

Source	Target	Alternative
Security Requirement Object `{name}`	Security Scheme Object name under the Components Object	n/a
Discriminator Object `mapping` (implicit, or explicit name syntax)	Schema Object name under the Components Object	`mapping` (explicit URI syntax)
Operation Object `tags`	Tag Object `name` (in the OpenAPI Object’s `tags` array)	n/a
Link Object `operationId`	Path Item Object `operationId`	`operationRef`

A fifth implicit connection involves appending the templated URL paths of the Paths Object to the appropriate Server Object’s url field. This is unambiguous because only the entry document’s Paths Object contributes URLs to the described API.

It is RECOMMENDED to consider all Operation Objects from all parsed documents when resolving any Link Object operationId. This requires parsing all referenced documents prior to determining an operationId to be unresolvable.

The implicit connections in the Security Requirement Object and Discriminator Object rely on the component name, which is the name of the property holding the component in the appropriately typed sub-object of the Components Object. For example, the component name of the Schema Object at #/components/schemas/Foo is Foo. The implicit connection of tags in the Operation Object uses the name field of Tag Objects, which (like the Components Object) are found under the root OpenAPI Object. This means resolving component names and tag names both depend on starting from the correct OpenAPI Object.

For resolving component and tag name connections from a referenced (non-entry) document, it is RECOMMENDED that tools resolve from the entry document, rather than the current document. This allows Security Scheme Objects and Tag Objects to be defined next to the API’s deployment information (the top-level array of Server Objects), and treated as an interface for referenced documents to access.

The interface approach can also work for Discriminator Objects and Schema Objects, but it is also possible to keep the Discriminator Object’s behavior within a single document using the relative URI-reference syntax of mapping.

There are no URI-based alternatives for the Security Requirement Object or for the Operation Object’s tags field. These limitations are expected to be addressed in a future release.

See Appendix F: Resolving Security Requirements in a Referenced Document for an example of the possible resolutions, including which one is recommended by this section. The behavior for Discrimator Object non-URI mappings and for the Operation Object’s tags field operate on the same principles.

Note that no aspect of implicit connection resolution changes how URIs are resolved, or restricts their possible targets.

Data types in the OAS are based on the types defined by the JSON Schema Validation Specification Draft 2020-12: “null”, “boolean”, “object”, “array”, “number”, “string”, or “integer”. Models are defined using the Schema Object, which is a superset of the JSON Schema Specification Draft 2020-12.

JSON Schema keywords and format values operate on JSON “instances” which may be one of the six JSON data types, “null”, “boolean”, “object”, “array”, “number”, or “string”, with certain keywords and formats only applying to a specific type. For example, the pattern keyword and the date-time format only apply to strings, and treat any instance of the other five types as automatically valid. This means JSON Schema keywords and formats do NOT implicitly require the expected type. Use the type keyword to explicitly constrain the type.

Note that the type keyword allows "integer" as a value for convenience, but keyword and format applicability does not recognize integers as being of a distinct JSON type from other numbers because JSON itself does not make that distinction. Since there is no distinct JSON integer type, JSON Schema defines integers mathematically. This means that both 1 and 1.0 are equivalent, and are both considered to be integers.

As defined by the JSON Schema Validation specification, data types can have an optional modifier keyword: format. As described in that specification, format is treated as a non-validating annotation by default; the ability to validate format varies across implementations.

The OpenAPI Initiative also hosts a Format Registry for formats defined by OAS users and other specifications. Support for any registered format is strictly OPTIONAL, and support for one registered format does not imply support for any others.

Types that are not accompanied by a format keyword follow the type definition in the JSON Schema. Tools that do not recognize a specific format MAY default back to the type alone, as if the format is not specified. For the purpose of JSON Schema validation, each format should specify the set of JSON data types for which it applies. In this registry, these types are shown in the “JSON Data Type” column.

The formats defined by the OAS are:

`format`	JSON Data Type	Comments
`int32`	number	signed 32 bits
`int64`	number	signed 64 bits (a.k.a long)
`float`	number
`double`	number
`password`	string	A hint to obscure the value.

As noted under Data Type, both type: number and type: integer are considered to be numbers in the data model.

The OAS can describe either raw or encoded binary data.

raw binary is used where unencoded binary data is allowed, such as when sending a binary payload as the entire HTTP message body, or as part of a multipart/* payload that allows binary parts
encoded binary is used where binary data is embedded in a text-only format such as application/json or application/x-www-form-urlencoded (either as a message body or in the URL query string).

In the following table showing how to use Schema Object keywords for binary data, we use image/png as an example binary media type. Any binary media type, including application/octet-stream, is sufficient to indicate binary content.

Keyword	Raw	Encoded	Comments
`type`	omit	`string`	raw binary is outside of `type`
`contentMediaType`	`image/png`	`image/png`	can sometimes be omitted if redundant (see below)
`contentEncoding`	omit	`base64` or `base64url`	other encodings are allowed

Note that the encoding indicated by contentEncoding, which inflates the size of data in order to represent it as 7-bit ASCII text, is unrelated to HTTP’s Content-Encoding header, which indicates whether and how a message body has been compressed and is applied after all content serialization described in this section has occurred. Since HTTP allows unencoded binary message bodies, there is no standardized HTTP header for indicating base64 or similar encoding of an entire message body.

Using a contentEncoding of base64url ensures that URL encoding (as required in the query string and in message bodies of type application/x-www-form-urlencoded) does not need to further encode any part of the already-encoded binary data.

The contentMediaType keyword is redundant if the media type is already set:

as the key for a MediaType Object
in the contentType field of an Encoding Object

If the Schema Object will be processed by a non-OAS-aware JSON Schema implementation, it may be useful to include contentMediaType even if it is redundant. However, if contentMediaType contradicts a relevant Media Type Object or Encoding Object, then contentMediaType SHALL be ignored.

The maxLength keyword MAY be used to set an expected upper bound on the length of a streaming payload. The keyword can be applied to either string data, including encoded binary data, or to unencoded binary data. For unencoded binary, the length is the number of octets.

The following table shows how to migrate from OAS 3.0 binary data descriptions, continuing to use image/png as the example binary media type:

OAS < 3.1	OAS 3.1	Comments
`type: string` `format: binary`	`contentMediaType: image/png`	if redundant, can be omitted, often resulting in an empty Schema Object
`type: string` `format: byte`	`type: string` `contentMediaType: image/png` `contentEncoding: base64`	note that `base64url` can be used to avoid re-encoding the base64 string to be URL-safe

Throughout the specification description fields are noted as supporting [CommonMark] markdown formatting. Where OpenAPI tooling renders rich text it MUST support, at a minimum, markdown syntax as described by [CommonMark-0.27]. Tooling MAY choose to ignore some CommonMark or extension features to address security concerns.

While the framing of CommonMark 0.27 as a minimum requirement means that tooling MAY choose to implement extensions on top of it, note that any such extensions are by definition implementation-defined and will not be interoperable. OpenAPI Description authors SHOULD consider how text using such extensions will be rendered by tools that offer only the minimum support.

URIs used as references within an OpenAPI Description, or to external documentation or other supplementary information such as a license, are resolved as identifiers, and described by this specification as URIs. As noted under Parsing Documents, this specification inherits JSON Schema Specification Draft 2020-12’s requirements for loading documents and associating them with their expected URIs, which might not match their current location. This feature is used both for working in development or test environments without having to change the URIs, and for working within restrictive network configurations or security policies.

Note that some URI fields are named url for historical reasons, but the descriptive text for those fields uses the correct “URI” terminology.

Unless specified otherwise, all fields that are URIs MAY be relative references as defined by [RFC3986] Section 4.2.

Relative references in Schema Objects, including any that appear as $id values, use the nearest parent $id as a Base URI, as described by JSON Schema Specification Draft 2020-12.

Relative URI references in other Objects, and in Schema Objects where no parent schema contains an $id, MUST be resolved using the referring document’s base URI, which is determined in accordance with [RFC3986] Section 5.1.2 – 5.1.4. In practice, this is usually the retrieval URI of the document, which MAY be determined based on either its current actual location or a user-supplied expected location.

If a URI contains a fragment identifier, then the fragment should be resolved per the fragment resolution mechanism of the referenced document. If the representation of the referenced document is JSON or YAML, then the fragment identifier SHOULD be interpreted as a JSON-Pointer as per [RFC6901].

Relative references in CommonMark hyperlinks are resolved in their rendered context, which might differ from the context of the API description.

API endpoints are by definition accessed as locations, and are described by this specification as URLs.

Unless specified otherwise, all fields that are URLs MAY be relative references as defined by [RFC3986] Section 4.2. Unless specified otherwise, relative references are resolved using the URLs defined in the Server Object as a Base URL. Note that these themselves MAY be relative to the referring document.

This section describes the structure of the OpenAPI Description format. This text is the only normative description of the format. A JSON Schema is hosted on spec.openapis.org for informational purposes. If the JSON Schema differs from this section, then this section MUST be considered authoritative.

In the following description, if a field is not explicitly REQUIRED or described with a MUST or SHALL, it can be considered OPTIONAL.

This is the root object of the OpenAPI Description.

Field Name	Type	Description
openapi	`string`	*REQUIRED. This string MUST* be the version number of the OpenAPI Specification that the OpenAPI Document uses. The `openapi` field SHOULD be used by tooling to interpret the OpenAPI Document. This is not related to the API `info.version` string.
info	Info Object	*REQUIRED. Provides metadata about the API. The metadata MAY* be used by tooling as required.
jsonSchemaDialect	`string`	The default value for the `$schema` keyword within Schema Objects contained within this OAS document. This MUST be in the form of a URI.
servers	[Server Object]	An array of Server Objects, which provide connectivity information to a target server. If the `servers` field is not provided, or is an empty array, the default value would be a Server Object with a url value of `/`.
paths	Paths Object	The available paths and operations for the API.
webhooks	Map[`string`, Path Item Object]	The incoming webhooks that MAY be received as part of this API and that the API consumer MAY choose to implement. Closely related to the `callbacks` feature, this section describes requests initiated other than by an API call, for example by an out of band registration. The key name is a unique string to refer to each webhook, while the (optionally referenced) Path Item Object describes a request that may be initiated by the API provider and the expected responses. An example is available.
components	Components Object	An element to hold various Objects for the OpenAPI Description.
security	[Security Requirement Object]	A declaration of which security mechanisms can be used across the API. The list of values includes alternative Security Requirement Objects that can be used. Only one of the Security Requirement Objects need to be satisfied to authorize a request. Individual operations can override this definition. The list can be incomplete, up to being empty or absent. To make security explicitly optional, an empty security requirement (`{}`) can be included in the array.
tags	[Tag Object]	A list of tags used by the OpenAPI Description with additional metadata. The order of the tags can be used to reflect on their order by the parsing tools. Not all tags that are used by the Operation Object must be declared. The tags that are not declared MAY be organized randomly or based on the tools’ logic. Each tag name in the list MUST be unique.
externalDocs	External Documentation Object	Additional external documentation.

This object MAY be extended with Specification Extensions.

The object provides metadata about the API. The metadata MAY be used by the clients if needed, and MAY be presented in editing or documentation generation tools for convenience.

Field Name	Type	Description
title	`string`	*REQUIRED*. The title of the API.
summary	`string`	A short summary of the API.
description	`string`	A description of the API. [CommonMark] syntax MAY be used for rich text representation.
termsOfService	`string`	A URI for the Terms of Service for the API. This MUST be in the form of a URI.
contact	Contact Object	The contact information for the exposed API.
license	License Object	The license information for the exposed API.
version	`string`	*REQUIRED*. The version of the OpenAPI Document (which is distinct from the OpenAPI Specification version or the version of the API being described or the version of the OpenAPI Description).

This object MAY be extended with Specification Extensions.

{
  "title": "Example Pet Store App",
  "summary": "A pet store manager.",
  "description": "This is an example server for a pet store.",
  "termsOfService": "https://example.com/terms/",
  "contact": {
    "name": "API Support",
    "url": "https://www.example.com/support",
    "email": "support@example.com"
  },
  "license": {
    "name": "Apache 2.0",
    "url": "https://www.apache.org/licenses/LICENSE-2.0.html"
  },
  "version": "1.0.1"
}

title: Example Pet Store App
summary: A pet store manager.
description: This is an example server for a pet store.
termsOfService: https://example.com/terms/
contact:
  name: API Support
  url: https://www.example.com/support
  email: support@example.com
license:
  name: Apache 2.0
  url: https://www.apache.org/licenses/LICENSE-2.0.html
version: 1.0.1

Contact information for the exposed API.

Field Name	Type	Description
name	`string`	The identifying name of the contact person/organization.
url	`string`	The URI for the contact information. This MUST be in the form of a URI.
email	`string`	The email address of the contact person/organization. This MUST be in the form of an email address.

This object MAY be extended with Specification Extensions.

{
  "name": "API Support",
  "url": "https://www.example.com/support",
  "email": "support@example.com"
}

name: API Support
url: https://www.example.com/support
email: support@example.com

License information for the exposed API.

Field Name	Type	Description
name	`string`	*REQUIRED*. The license name used for the API.
identifier	`string`	An [SPDX-Licenses] expression for the API. The `identifier` field is mutually exclusive of the `url` field.
url	`string`	A URI for the license used for the API. This MUST be in the form of a URI. The `url` field is mutually exclusive of the `identifier` field.

This object MAY be extended with Specification Extensions.

{
  "name": "Apache 2.0",
  "identifier": "Apache-2.0"
}

name: Apache 2.0
identifier: Apache-2.0

An object representing a Server.

Field Name	Type	Description
url	`string`	*REQUIRED. A URL to the target host. This URL supports Server Variables and MAY* be relative, to indicate that the host location is relative to the location where the document containing the Server Object is being served. Variable substitutions will be made when a variable is named in `{`braces`}`.
description	`string`	An optional string describing the host designated by the URL. [CommonMark] syntax MAY be used for rich text representation.
variables	Map[`string`, Server Variable Object]	A map between a variable name and its value. The value is used for substitution in the server’s URL template.

This object MAY be extended with Specification Extensions.

A single server would be described as:

{
  "url": "https://development.gigantic-server.com/v1",
  "description": "Development server"
}

url: https://development.gigantic-server.com/v1
description: Development server

The following shows how multiple servers can be described, for example, at the OpenAPI Object’s servers:

{
  "servers": [
    {
      "url": "https://development.gigantic-server.com/v1",
      "description": "Development server"
    },
    {
      "url": "https://staging.gigantic-server.com/v1",
      "description": "Staging server"
    },
    {
      "url": "https://api.gigantic-server.com/v1",
      "description": "Production server"
    }
  ]
}

servers:
  - url: https://development.gigantic-server.com/v1
    description: Development server
  - url: https://staging.gigantic-server.com/v1
    description: Staging server
  - url: https://api.gigantic-server.com/v1
    description: Production server

The following shows how variables can be used for a server configuration:

{
  "servers": [
    {
      "url": "https://{username}.gigantic-server.com:{port}/{basePath}",
      "description": "The production API server",
      "variables": {
        "username": {
          "default": "demo",
          "description": "A user-specific subdomain. Use `demo` for a free sandbox environment."
        },
        "port": {
          "enum": ["8443", "443"],
          "default": "8443"
        },
        "basePath": {
          "default": "v2"
        }
      }
    }
  ]
}

servers:
  - url: https://{username}.gigantic-server.com:{port}/{basePath}
    description: The production API server
    variables:
      username:
        # note! no enum here means it is an open value
        default: demo
        description: A user-specific subdomain. Use `demo` for a free sandbox environment.
      port:
        enum:
          - '8443'
          - '443'
        default: '8443'
      basePath:
        # open meaning there is the opportunity to use special base paths as assigned by the provider, default is `v2`
        default: v2

An object representing a Server Variable for server URL template substitution.

Field Name	Type	Description
enum	[`string`]	An enumeration of string values to be used if the substitution options are from a limited set. The array MUST NOT be empty.
default	`string`	*REQUIRED. The default value to use for substitution, which SHALL* be sent if an alternate value is not supplied. If the `enum` is defined, the value MUST exist in the enum’s values. Note that this behavior is different from the Schema Object’s `default` keyword, which documents the receiver’s behavior rather than inserting the value into the data.
description	`string`	An optional description for the server variable. [CommonMark] syntax MAY be used for rich text representation.

This object MAY be extended with Specification Extensions.

Holds a set of reusable objects for different aspects of the OAS. All objects defined within the Components Object will have no effect on the API unless they are explicitly referenced from outside the Components Object.

Field Name	Type	Description
schemas	Map[`string`, Schema Object]	An object to hold reusable Schema Objects.
responses	Map[`string`, Response Object \| Reference Object]	An object to hold reusable Response Objects.
parameters	Map[`string`, Parameter Object \| Reference Object]	An object to hold reusable Parameter Objects.
examples	Map[`string`, Example Object \| Reference Object]	An object to hold reusable Example Objects.
requestBodies	Map[`string`, Request Body Object \| Reference Object]	An object to hold reusable Request Body Objects.
headers	Map[`string`, Header Object \| Reference Object]	An object to hold reusable Header Objects.
securitySchemes	Map[`string`, Security Scheme Object \| Reference Object]	An object to hold reusable Security Scheme Objects.
links	Map[`string`, Link Object \| Reference Object]	An object to hold reusable Link Objects.
callbacks	Map[`string`, Callback Object \| Reference Object]	An object to hold reusable Callback Objects.
pathItems	Map[`string`, Path Item Object]	An object to hold reusable Path Item Objects.

This object MAY be extended with Specification Extensions.

All the fixed fields declared above are objects that MUST use keys that match the regular expression: ^[a-zA-Z0-9\.\-_]+$.

Field Name Examples:

User
User_1
User_Name
user-name
my.org.User

"components": {
  "schemas": {
    "GeneralError": {
      "type": "object",
      "properties": {
        "code": {
          "type": "integer",
          "format": "int32"
        },
        "message": {
          "type": "string"
        }
      }
    },
    "Category": {
      "type": "object",
      "properties": {
        "id": {
          "type": "integer",
          "format": "int64"
        },
        "name": {
          "type": "string"
        }
      }
    },
    "Tag": {
      "type": "object",
      "properties": {
        "id": {
          "type": "integer",
          "format": "int64"
        },
        "name": {
          "type": "string"
        }
      }
    }
  },
  "parameters": {
    "skipParam": {
      "name": "skip",
      "in": "query",
      "description": "number of items to skip",
      "required": true,
      "schema": {
        "type": "integer",
        "format": "int32"
      }
    },
    "limitParam": {
      "name": "limit",
      "in": "query",
      "description": "max records to return",
      "required": true,
      "schema" : {
        "type": "integer",
        "format": "int32"
      }
    }
  },
  "responses": {
    "NotFound": {
      "description": "Entity not found."
    },
    "IllegalInput": {
      "description": "Illegal input for operation."
    },
    "GeneralError": {
      "description": "General Error",
      "content": {
        "application/json": {
          "schema": {
            "$ref": "#/components/schemas/GeneralError"
          }
        }
      }
    }
  },
  "securitySchemes": {
    "api_key": {
      "type": "apiKey",
      "name": "api-key",
      "in": "header"
    },
    "petstore_auth": {
      "type": "oauth2",
      "flows": {
        "implicit": {
          "authorizationUrl": "https://example.org/api/oauth/dialog",
          "scopes": {
            "write:pets": "modify pets in your account",
            "read:pets": "read your pets"
          }
        }
      }
    }
  }
}

components:
  schemas:
    GeneralError:
      type: object
      properties:
        code:
          type: integer
          format: int32
        message:
          type: string
    Category:
      type: object
      properties:
        id:
          type: integer
          format: int64
        name:
          type: string
    Tag:
      type: object
      properties:
        id:
          type: integer
          format: int64
        name:
          type: string
  parameters:
    skipParam:
      name: skip
      in: query
      description: number of items to skip
      required: true
      schema:
        type: integer
        format: int32
    limitParam:
      name: limit
      in: query
      description: max records to return
      required: true
      schema:
        type: integer
        format: int32
  responses:
    NotFound:
      description: Entity not found.
    IllegalInput:
      description: Illegal input for operation.
    GeneralError:
      description: General Error
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/GeneralError'
  securitySchemes:
    api_key:
      type: apiKey
      name: api-key
      in: header
    petstore_auth:
      type: oauth2
      flows:
        implicit:
          authorizationUrl: https://example.org/api/oauth/dialog
          scopes:
            write:pets: modify pets in your account
            read:pets: read your pets

Holds the relative paths to the individual endpoints and their operations. The path is appended to the URL from the Server Object in order to construct the full URL. The Paths Object MAY be empty, due to Access Control List (ACL) constraints.

Field Pattern	Type	Description
/{path}	Path Item Object	A relative path to an individual endpoint. The field name MUST begin with a forward slash (`/`). The path is appended (no relative URL resolution) to the expanded URL from the Server Object’s `url` field in order to construct the full URL. Path templating is allowed. When matching URLs, concrete (non-templated) paths would be matched before their templated counterparts. Templated paths with the same hierarchy but different templated names MUST NOT exist as they are identical. In case of ambiguous matching, it’s up to the tooling to decide which one to use.

This object MAY be extended with Specification Extensions.

Assuming the following paths, the concrete definition, /pets/mine, will be matched first if used:

  /pets/{petId}
  /pets/mine

The following paths are considered identical and invalid:

  /pets/{petId}
  /pets/{name}

The following may lead to ambiguous resolution:

  /{entity}/me
  /books/{id}

{
  "/pets": {
    "get": {
      "description": "Returns all pets from the system that the user has access to",
      "responses": {
        "200": {
          "description": "A list of pets.",
          "content": {
            "application/json": {
              "schema": {
                "type": "array",
                "items": {
                  "$ref": "#/components/schemas/pet"
                }
              }
            }
          }
        }
      }
    }
  }
}

/pets:
  get:
    description: Returns all pets from the system that the user has access to
    responses:
      '200':
        description: A list of pets.
        content:
          application/json:
            schema:
              type: array
              items:
                $ref: '#/components/schemas/pet'

Describes the operations available on a single path. A Path Item MAY be empty, due to ACL constraints. The path itself is still exposed to the documentation viewer but they will not know which operations and parameters are available.

Field Name	Type	Description
$ref	`string`	Allows for a referenced definition of this path item. The value MUST be in the form of a URI, and the referenced structure MUST be in the form of a Path Item Object. In case a Path Item Object field appears both in the defined object and the referenced object, the behavior is undefined. See the rules for resolving Relative References. Note: The behavior of `$ref` with adjacent properties is likely to change in future versions of this specification to bring it into closer alignment with the behavior of the Reference Object.
summary	`string`	An optional string summary, intended to apply to all operations in this path.
description	`string`	An optional string description, intended to apply to all operations in this path. [CommonMark] syntax MAY be used for rich text representation.
get	Operation Object	A definition of a GET operation on this path.
put	Operation Object	A definition of a PUT operation on this path.
post	Operation Object	A definition of a POST operation on this path.
delete	Operation Object	A definition of a DELETE operation on this path.
options	Operation Object	A definition of a OPTIONS operation on this path.
head	Operation Object	A definition of a HEAD operation on this path.
patch	Operation Object	A definition of a PATCH operation on this path.
trace	Operation Object	A definition of a TRACE operation on this path.
servers	[Server Object]	An alternative `servers` array to service all operations in this path. If a `servers` array is specified at the OpenAPI Object level, it will be overridden by this value.
parameters	[Parameter Object \| Reference Object]	A list of parameters that are applicable for all the operations described under this path. These parameters can be overridden at the operation level, but cannot be removed there. The list MUST NOT include duplicated parameters. A unique parameter is defined by a combination of a name and location. The list can use the Reference Object to link to parameters that are defined in the OpenAPI Object’s `components.parameters`.

This object MAY be extended with Specification Extensions.

{
  "get": {
    "description": "Returns pets based on ID",
    "summary": "Find pets by ID",
    "operationId": "getPetsById",
    "responses": {
      "200": {
        "description": "pet response",
        "content": {
          "*/*": {
            "schema": {
              "type": "array",
              "items": {
                "$ref": "#/components/schemas/Pet"
              }
            }
          }
        }
      },
      "default": {
        "description": "error payload",
        "content": {
          "text/html": {
            "schema": {
              "$ref": "#/components/schemas/ErrorModel"
            }
          }
        }
      }
    }
  },
  "parameters": [
    {
      "name": "id",
      "in": "path",
      "description": "ID of pet to use",
      "required": true,
      "schema": {
        "type": "array",
        "items": {
          "type": "string"
        }
      },
      "style": "simple"
    }
  ]
}

get:
  description: Returns pets based on ID
  summary: Find pets by ID
  operationId: getPetsById
  responses:
    '200':
      description: pet response
      content:
        '*/*':
          schema:
            type: array
            items:
              $ref: '#/components/schemas/Pet'
    default:
      description: error payload
      content:
        text/html:
          schema:
            $ref: '#/components/schemas/ErrorModel'
parameters:
  - name: id
    in: path
    description: ID of pet to use
    required: true
    schema:
      type: array
      items:
        type: string
    style: simple

Describes a single API operation on a path.

Field Name	Type	Description
tags	[`string`]	A list of tags for API documentation control. Tags can be used for logical grouping of operations by resources or any other qualifier.
summary	`string`	A short summary of what the operation does.
description	`string`	A verbose explanation of the operation behavior. [CommonMark] syntax MAY be used for rich text representation.
externalDocs	External Documentation Object	Additional external documentation for this operation.
operationId	`string`	Unique string used to identify the operation. The id MUST be unique among all operations described in the API. The operationId value is case-sensitive. Tools and libraries MAY use the operationId to uniquely identify an operation, therefore, it is RECOMMENDED to follow common programming naming conventions.
parameters	[Parameter Object \| Reference Object]	A list of parameters that are applicable for this operation. If a parameter is already defined at the Path Item, the new definition will override it but can never remove it. The list MUST NOT include duplicated parameters. A unique parameter is defined by a combination of a name and location. The list can use the Reference Object to link to parameters that are defined in the OpenAPI Object’s `components.parameters`.
requestBody	Request Body Object \| Reference Object	The request body applicable for this operation. The `requestBody` is fully supported in HTTP methods where the HTTP 1.1 specification [RFC7231] Section 4.3.1 has explicitly defined semantics for request bodies. In other cases where the HTTP spec is vague (such as GET, HEAD and DELETE), `requestBody` is permitted but does not have well-defined semantics and SHOULD be avoided if possible.
responses	Responses Object	The list of possible responses as they are returned from executing this operation.
callbacks	Map[`string`, Callback Object \| Reference Object]	A map of possible out-of band callbacks related to the parent operation. The key is a unique identifier for the Callback Object. Each value in the map is a Callback Object that describes a request that may be initiated by the API provider and the expected responses.
deprecated	`boolean`	Declares this operation to be deprecated. Consumers SHOULD refrain from usage of the declared operation. Default value is `false`.
security	[Security Requirement Object]	A declaration of which security mechanisms can be used for this operation. The list of values includes alternative Security Requirement Objects that can be used. Only one of the Security Requirement Objects need to be satisfied to authorize a request. To make security optional, an empty security requirement (`{}`) can be included in the array. This definition overrides any declared top-level `security`. To remove a top-level security declaration, an empty array can be used.
servers	[Server Object]	An alternative `servers` array to service this operation. If a `servers` array is specified at the Path Item Object or OpenAPI Object level, it will be overridden by this value.

This object MAY be extended with Specification Extensions.

{
  "tags": ["pet"],
  "summary": "Updates a pet in the store with form data",
  "operationId": "updatePetWithForm",
  "parameters": [
    {
      "name": "petId",
      "in": "path",
      "description": "ID of pet that needs to be updated",
      "required": true,
      "schema": {
        "type": "string"
      }
    }
  ],
  "requestBody": {
    "content": {
      "application/x-www-form-urlencoded": {
        "schema": {
          "type": "object",
          "properties": {
            "name": {
              "description": "Updated name of the pet",
              "type": "string"
            },
            "status": {
              "description": "Updated status of the pet",
              "type": "string"
            }
          },
          "required": ["status"]
        }
      }
    }
  },
  "responses": {
    "200": {
      "description": "Pet updated.",
      "content": {
        "application/json": {},
        "application/xml": {}
      }
    },
    "405": {
      "description": "Method Not Allowed",
      "content": {
        "application/json": {},
        "application/xml": {}
      }
    }
  },
  "security": [
    {
      "petstore_auth": ["write:pets", "read:pets"]
    }
  ]
}

tags:
  - pet
summary: Updates a pet in the store with form data
operationId: updatePetWithForm
parameters:
  - name: petId
    in: path
    description: ID of pet that needs to be updated
    required: true
    schema:
      type: string
requestBody:
  content:
    application/x-www-form-urlencoded:
      schema:
        type: object
        properties:
          name:
            description: Updated name of the pet
            type: string
          status:
            description: Updated status of the pet
            type: string
        required:
          - status
responses:
  '200':
    description: Pet updated.
    content:
      application/json: {}
      application/xml: {}
  '405':
    description: Method Not Allowed
    content:
      application/json: {}
      application/xml: {}
security:
  - petstore_auth:
      - write:pets
      - read:pets

Allows referencing an external resource for extended documentation.

Field Name	Type	Description
description	`string`	A description of the target documentation. [CommonMark] syntax MAY be used for rich text representation.
url	`string`	*REQUIRED. The URI for the target documentation. This MUST* be in the form of a URI.

This object MAY be extended with Specification Extensions.

{
  "description": "Find more info here",
  "url": "https://example.com"
}

description: Find more info here
url: https://example.com

Describes a single operation parameter.

A unique parameter is defined by a combination of a name and location.

See Appendix E for a detailed examination of percent-encoding concerns, including interactions with the application/x-www-form-urlencoded query string format.

There are four possible parameter locations specified by the in field:

path - Used together with Path Templating, where the parameter value is actually part of the operation’s URL. This does not include the host or base path of the API. For example, in /items/{itemId}, the path parameter is itemId.
query - Parameters that are appended to the URL. For example, in /items?id=###, the query parameter is id.
header - Custom headers that are expected as part of the request. Note that [RFC7230] Section 3.2 states header names are case insensitive.
cookie - Used to pass a specific cookie value to the API.

The rules for serialization of the parameter are specified in one of two ways. Parameter Objects MUST include either a content field or a schema field, but not both. See Appendix B for a discussion of converting values of various types to string representations.

These fields MAY be used with either content or schema.

Field Name	Type	Description
name	`string`	*REQUIRED. The name of the parameter. Parameter names are case sensitive. If `in` is `"path"`, the `name` field MUST* correspond to a template expression occurring within the path field in the Paths Object. See Path Templating for further information. If `in` is `"header"` and the `name` field is `"Accept"`, `"Content-Type"` or `"Authorization"`, the parameter definition SHALL be ignored. For all other cases, the `name` corresponds to the parameter name used by the `in` field.
in	`string`	*REQUIRED*. The location of the parameter. Possible values are `"query"`, `"header"`, `"path"` or `"cookie"`.
description	`string`	A brief description of the parameter. This could contain examples of use. [CommonMark] syntax MAY be used for rich text representation.
required	`boolean`	Determines whether this parameter is mandatory. If the parameter location is `"path"`, this field is *REQUIRED* and its value MUST be `true`. Otherwise, the field MAY be included and its default value is `false`.
deprecated	`boolean`	Specifies that a parameter is deprecated and SHOULD be transitioned out of usage. Default value is `false`.
allowEmptyValue	`boolean`	If `true`, clients MAY pass a zero-length string value in place of parameters that would otherwise be omitted entirely, which the server SHOULD interpret as the parameter being unused. Default value is `false`. If `style` is used, and if behavior is n/a (cannot be serialized), the value of `allowEmptyValue` SHALL be ignored. Interactions between this field and the parameter’s Schema Object are implementation-defined. This field is valid only for `query` parameters. Use of this field is NOT RECOMMENDED, and it is likely to be removed in a later revision.

This object MAY be extended with Specification Extensions.

Note that while "Cookie" as a name is not forbidden if in is "header", the effect of defining a cookie parameter that way is undefined; use in: "cookie" instead.

For simpler scenarios, a schema and style can describe the structure and syntax of the parameter. When example or examples are provided in conjunction with the schema field, the example SHOULD match the specified schema and follow the prescribed serialization strategy for the parameter. The example and examples fields are mutually exclusive, and if either is present it SHALL override any example in the schema.

Serializing with schema is NOT RECOMMENDED for in: "cookie" parameters, in: "header" parameters that use HTTP header parameters (name=value pairs following a ;) in their values, or in: "header" parameters where values might have non-URL-safe characters; see Appendix D for details.

Field Name	Type	Description
style	`string`	Describes how the parameter value will be serialized depending on the type of the parameter value. Default values (based on value of `in`): for `"query"` - `"form"`; for `"path"` - `"simple"`; for `"header"` - `"simple"`; for `"cookie"` - `"form"`.
explode	`boolean`	When this is true, parameter values of type `array` or `object` generate separate parameters for each value of the array or key-value pair of the map. For other types of parameters this field has no effect. When `style` is `"form"`, the default value is `true`. For all other styles, the default value is `false`. Note that despite `false` being the default for `deepObject`, the combination of `false` with `deepObject` is undefined.
allowReserved	`boolean`	When this is true, parameter values are serialized using reserved expansion, as defined by [RFC6570] Section 3.2.3, which allows RFC3986’s reserved character set, as well as percent-encoded triples, to pass through unchanged, while still percent-encoding all other disallowed characters (including `%` outside of percent-encoded triples). Applications are still responsible for percent-encoding reserved characters that are not allowed in the query string (`[`, `]`, `#`), or have a special meaning in `application/x-www-form-urlencoded` (`-`, `&`, `+`); see Appendices C and E for details. This field only applies to parameters with an `in` value of `query`. The default value is `false`.
schema	Schema Object	The schema defining the type used for the parameter.
example	Any	Example of the parameter’s potential value; see Working With Examples.
examples	Map[ `string`, Example Object \| Reference Object]	Examples of the parameter’s potential value; see Working With Examples.

See also Appendix C: Using RFC6570-Based Serialization for additional guidance.

For more complex scenarios, the content field can define the media type and schema of the parameter, as well as give examples of its use. Using content with a text/plain media type is RECOMMENDED for in: "header" and in: "cookie" parameters where the schema strategy is not appropriate.

Field Name	Type	Description
content	Map[`string`, Media Type Object]	A map containing the representations for the parameter. The key is the media type and the value describes it. The map MUST only contain one entry.

In order to support common ways of serializing simple parameters, a set of style values are defined.

`style`	`type`	`in`	Comments
matrix	`primitive`, `array`, `object`	`path`	Path-style parameters defined by [RFC6570] Section 3.2.7
label	`primitive`, `array`, `object`	`path`	Label style parameters defined by [RFC6570] Section 3.2.5
simple	`primitive`, `array`, `object`	`path`, `header`	Simple style parameters defined by [RFC6570] Section 3.2.2. This option replaces `collectionFormat` with a `csv` value from OpenAPI 2.0.
form	`primitive`, `array`, `object`	`query`, `cookie`	Form style parameters defined by [RFC6570] Section 3.2.8. This option replaces `collectionFormat` with a `csv` (when `explode` is false) or `multi` (when `explode` is true) value from OpenAPI 2.0.
spaceDelimited	`array`, `object`	`query`	Space separated array values or object properties and values. This option replaces `collectionFormat` equal to `ssv` from OpenAPI 2.0.
pipeDelimited	`array`, `object`	`query`	Pipe separated array values or object properties and values. This option replaces `collectionFormat` equal to `pipes` from OpenAPI 2.0.
deepObject	`object`	`query`	Allows objects with scalar properties to be represented using form parameters. The representation of array or object properties is not defined.

See Appendix E for a discussion of percent-encoding, including when delimiters need to be percent-encoded and options for handling collisions with percent-encoded data.

Assume a parameter named color has one of the following values:

   string -> "blue"
   array -> ["blue", "black", "brown"]
   object -> { "R": 100, "G": 200, "B": 150 }

The following table shows examples, as would be shown with the example or examples keywords, of the different serializations for each value.

The value empty denotes the empty string, and is unrelated to the allowEmptyValue field
The behavior of combinations marked n/a is undefined
The undefined column replaces the empty column in previous versions of this specification in order to better align with [RFC6570] Section 2.3 terminology, which describes certain values including but not limited to null as “undefined” values with special handling; notably, the empty string is not undefined
For form and the non-RFC6570 query string styles spaceDelimited, pipeDelimited, and deepObject, each example is shown prefixed with ? as if it were the only query parameter; see Appendix C for more information on constructing query strings from multiple parameters, and Appendix D for warnings regarding form and cookie parameters
Note that the ? prefix is not appropriate for serializing application/x-www-form-urlencoded HTTP message bodies, and MUST be stripped or (if constructing the string manually) not added when used in that context; see the Encoding Object for more information
The examples are percent-encoded as required by RFC6570 and RFC3986; see Appendix E for a thorough discussion of percent-encoding concerns, including why unencoded | (%7C), [ (%5B), and ] (%5D) seem to work in some environments despite not being compliant.

`style`	`explode`	`undefined`	`string`	`array`	`object`
matrix	false	;color	;color=blue	;color=blue,black,brown	;color=R,100,G,200,B,150
matrix	true	;color	;color=blue	;color=blue;color=black;color=brown	;R=100;G=200;B=150
label	false	.	.blue	.blue,black,brown	.R,100,G,200,B,150
label	true	.	.blue	.blue.black.brown	.R=100.G=200.B=150
simple	false	empty	blue	blue,black,brown	R,100,G,200,B,150
simple	true	empty	blue	blue,black,brown	R=100,G=200,B=150
form	false	?color=	?color=blue	?color=blue,black,brown	?color=R,100,G,200,B,150
form	true	?color=	?color=blue	?color=blue&color=black&color=brown	?R=100&G=200&B=150
spaceDelimited	false	n/a	n/a	?color=blue%20black%20brown	?color=R%20100%20G%20200%20B%20150
spaceDelimited	true	n/a	n/a	n/a	n/a
pipeDelimited	false	n/a	n/a	?color=blue%7Cblack%7Cbrown	?color=R%7C100%7CG%7C200%7CB%7C150
pipeDelimited	true	n/a	n/a	n/a	n/a
deepObject	false	n/a	n/a	n/a	n/a
deepObject	true	n/a	n/a	n/a	?color%5BR%5D=100&color%5BG%5D=200&color%5BB%5D=150

A header parameter with an array of 64-bit integer numbers:

{
  "name": "token",
  "in": "header",
  "description": "token to be passed as a header",
  "required": true,
  "schema": {
    "type": "array",
    "items": {
      "type": "integer",
      "format": "int64"
    }
  },
  "style": "simple"
}

name: token
in: header
description: token to be passed as a header
required: true
schema:
  type: array
  items:
    type: integer
    format: int64
style: simple

A path parameter of a string value:

{
  "name": "username",
  "in": "path",
  "description": "username to fetch",
  "required": true,
  "schema": {
    "type": "string"
  }
}

name: username
in: path
description: username to fetch
required: true
schema:
  type: string

An optional query parameter of a string value, allowing multiple values by repeating the query parameter:

{
  "name": "id",
  "in": "query",
  "description": "ID of the object to fetch",
  "required": false,
  "schema": {
    "type": "array",
    "items": {
      "type": "string"
    }
  },
  "style": "form",
  "explode": true
}

name: id
in: query
description: ID of the object to fetch
required: false
schema:
  type: array
  items:
    type: string
style: form
explode: true

A free-form query parameter, allowing undefined parameters of a specific type:

{
  "in": "query",
  "name": "freeForm",
  "schema": {
    "type": "object",
    "additionalProperties": {
      "type": "integer"
    }
  },
  "style": "form"
}

in: query
name: freeForm
schema:
  type: object
  additionalProperties:
    type: integer
style: form

A complex parameter using content to define serialization:

{
  "in": "query",
  "name": "coordinates",
  "content": {
    "application/json": {
      "schema": {
        "type": "object",
        "required": ["lat", "long"],
        "properties": {
          "lat": {
            "type": "number"
          },
          "long": {
            "type": "number"
          }
        }
      }
    }
  }
}

in: query
name: coordinates
content:
  application/json:
    schema:
      type: object
      required:
        - lat
        - long
      properties:
        lat:
          type: number
        long:
          type: number

Describes a single request body.

Field Name	Type	Description
description	`string`	A brief description of the request body. This could contain examples of use. [CommonMark] syntax MAY be used for rich text representation.
content	Map[`string`, Media Type Object]	*REQUIRED. The content of the request body. The key is a media type or media type range, see [RFC7231] Appendix D, and the value describes it. For requests that match multiple keys, only the most specific key is applicable. e.g. `"text/plain"` overrides `"text/"`
required	`boolean`	Determines if the request body is required in the request. Defaults to `false`.

This object MAY be extended with Specification Extensions.

A request body with a referenced schema definition.

{
  "description": "user to add to the system",
  "content": {
    "application/json": {
      "schema": {
        "$ref": "#/components/schemas/User"
      },
      "examples": {
        "user": {
          "summary": "User Example",
          "externalValue": "https://foo.bar/examples/user-example.json"
        }
      }
    },
    "application/xml": {
      "schema": {
        "$ref": "#/components/schemas/User"
      },
      "examples": {
        "user": {
          "summary": "User example in XML",
          "externalValue": "https://foo.bar/examples/user-example.xml"
        }
      }
    },
    "text/plain": {
      "examples": {
        "user": {
          "summary": "User example in Plain text",
          "externalValue": "https://foo.bar/examples/user-example.txt"
        }
      }
    },
    "*/*": {
      "examples": {
        "user": {
          "summary": "User example in other format",
          "externalValue": "https://foo.bar/examples/user-example.whatever"
        }
      }
    }
  }
}

description: user to add to the system
content:
  application/json:
    schema:
      $ref: '#/components/schemas/User'
    examples:
      user:
        summary: User example
        externalValue: https://foo.bar/examples/user-example.json
  application/xml:
    schema:
      $ref: '#/components/schemas/User'
    examples:
      user:
        summary: User example in XML
        externalValue: https://foo.bar/examples/user-example.xml
  text/plain:
    examples:
      user:
        summary: User example in plain text
        externalValue: https://foo.bar/examples/user-example.txt
  '*/*':
    examples:
      user:
        summary: User example in other format
        externalValue: https://foo.bar/examples/user-example.whatever

Each Media Type Object provides schema and examples for the media type identified by its key.

When example or examples are provided, the example SHOULD match the specified schema and be in the correct format as specified by the media type and its encoding. The example and examples fields are mutually exclusive, and if either is present it SHALL override any example in the schema. See Working With Examples for further guidance regarding the different ways of specifying examples, including non-JSON/YAML values.

Field Name	Type	Description
schema	Schema Object	The schema defining the content of the request, response, parameter, or header.
example	Any	Example of the media type; see Working With Examples.
examples	Map[ `string`, Example Object \| Reference Object]	Examples of the media type; see Working With Examples.
encoding	Map[`string`, Encoding Object]	A map between a property name and its encoding information. The key, being the property name, MUST exist in the schema as a property. The `encoding` field SHALL only apply to Request Body Objects, and only when the media type is `multipart` or `application/x-www-form-urlencoded`. If no Encoding Object is provided for a property, the behavior is determined by the default values documented for the Encoding Object.

This object MAY be extended with Specification Extensions.

{
  "application/json": {
    "schema": {
      "$ref": "#/components/schemas/Pet"
    },
    "examples": {
      "cat": {
        "summary": "An example of a cat",
        "value": {
          "name": "Fluffy",
          "petType": "Cat",
          "color": "White",
          "gender": "male",
          "breed": "Persian"
        }
      },
      "dog": {
        "summary": "An example of a dog with a cat's name",
        "value": {
          "name": "Puma",
          "petType": "Dog",
          "color": "Black",
          "gender": "Female",
          "breed": "Mixed"
        }
      },
      "frog": {
        "$ref": "#/components/examples/frog-example"
      }
    }
  }
}

application/json:
  schema:
    $ref: '#/components/schemas/Pet'
  examples:
    cat:
      summary: An example of a cat
      value:
        name: Fluffy
        petType: Cat
        color: White
        gender: male
        breed: Persian
    dog:
      summary: An example of a dog with a cat's name
      value:
        name: Puma
        petType: Dog
        color: Black
        gender: Female
        breed: Mixed
    frog:
      $ref: '#/components/examples/frog-example'

In contrast to OpenAPI 2.0, file input/output content in OAS 3.x is described with the same semantics as any other schema type.

In contrast to OAS 3.0, the format keyword has no effect on the content-encoding of the schema in OAS 3.1. Instead, JSON Schema’s contentEncoding and contentMediaType keywords are used. See Working With Binary Data for how to model various scenarios with these keywords, and how to migrate from the previous format usage.

Examples:

Content transferred in binary (octet-stream) MAY omit schema:

# a PNG image as a binary file:
content:
  image/png: {}

# an arbitrary binary file:
content:
  application/octet-stream: {}

# arbitrary JSON without constraints beyond being syntactically valid:
content:
  application/json: {}

These examples apply to either input payloads of file uploads or response payloads.

A requestBody for submitting a file in a POST operation may look like the following example:

requestBody:
  content:
    application/octet-stream: {}

In addition, specific media types MAY be specified:

# multiple, specific media types may be specified:
requestBody:
  content:
    # a binary file of type png or jpeg
    image/jpeg: {}
    image/png: {}

To upload multiple files, a multipart media type MUST be used as shown under Example: Multipart Form with Multiple Files.

See Encoding the x-www-form-urlencoded Media Type for guidance and examples, both with and without the encoding field.

See Encoding multipart Media Types for further guidance and examples, both with and without the encoding field.

A single encoding definition applied to a single schema property. See Appendix B for a discussion of converting values of various types to string representations.

Properties are correlated with multipart parts using the name parameter of Content-Disposition: form-data, and with application/x-www-form-urlencoded using the query string parameter names. In both cases, their order is implementation-defined.

See Appendix E for a detailed examination of percent-encoding concerns for form media types.

These fields MAY be used either with or without the RFC6570-style serialization fields defined in the next section below.

Field Name	Type	Description
contentType	`string`	The `Content-Type` for encoding a specific property. The value is a comma-separated list, each element of which is either a specific media type (e.g. `image/png`) or a wildcard media type (e.g. `image/*`). Default value depends on the property type as shown in the table below.
headers	Map[`string`, Header Object \| Reference Object]	A map allowing additional information to be provided as headers. `Content-Type` is described separately and SHALL be ignored in this section. This field SHALL be ignored if the request body media type is not a `multipart`.

This object MAY be extended with Specification Extensions.

The default values for contentType are as follows, where an n/a in the contentEncoding column means that the presence or value of contentEncoding is irrelevant:

`type`	`contentEncoding`	Default `contentType`
absent	n/a	`application/octet-stream`
`string`	present	`application/octet-stream`
`string`	absent	`text/plain`
`number`, `integer`, or `boolean`	n/a	`text/plain`
`object`	n/a	`application/json`
`array`	n/a	according to the `type` of the `items` schema

Determining how to handle a type value of null depends on how null values are being serialized. If null values are entirely omitted, then the contentType is irrelevant. See Appendix B for a discussion of data type conversion options.

Field Name	Type	Description
style	`string`	Describes how a specific property value will be serialized depending on its type. See Parameter Object for details on the `style` field. The behavior follows the same values as `query` parameters, including default values. Note that the initial `?` used in query strings is not used in `application/x-www-form-urlencoded` message bodies, and MUST be removed (if using an RFC6570 implementation) or simply not added (if constructing the string manually). This field SHALL be ignored if the request body media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of `contentType` (implicit or explicit) SHALL be ignored.
explode	`boolean`	When this is true, property values of type `array` or `object` generate separate parameters for each value of the array, or key-value-pair of the map. For other types of properties this field has no effect. When `style` is `"form"`, the default value is `true`. For all other styles, the default value is `false`. Note that despite `false` being the default for `deepObject`, the combination of `false` with `deepObject` is undefined. This field SHALL be ignored if the request body media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of `contentType` (implicit or explicit) SHALL be ignored.
allowReserved	`boolean`	When this is true, parameter values are serialized using reserved expansion, as defined by [RFC6570] Section 3.2.3, which allows RFC3986’s reserved character set, as well as percent-encoded triples, to pass through unchanged, while still percent-encoding all other disallowed characters (including `%` outside of percent-encoded triples). Applications are still responsible for percent-encoding reserved characters that are not allowed in the query string (`[`, `]`, `#`), or have a special meaning in `application/x-www-form-urlencoded` (`-`, `&`, `+`); see Appendices C and E for details. The default value is `false`. This field SHALL be ignored if the request body media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of `contentType` (implicit or explicit) SHALL be ignored.

See also Appendix C: Using RFC6570 Implementations for additional guidance, including on difficulties caused by the interaction between RFC6570’s percent-encoding rules and the multipart/form-data media type.

Note that the presence of at least one of style, explode, or allowReserved with an explicit value is equivalent to using schema with in: "query" Parameter Objects. The absence of all three of those fields is the equivalent of using content, but with the media type specified in contentType rather than through a Media Type Object.

To submit content using form url encoding via [RFC1866], use the application/x-www-form-urlencoded media type in the Media Type Object under the Request Body Object. This configuration means that the request body MUST be encoded per [RFC1866] when passed to the server, after any complex objects have been serialized to a string representation.

See Appendix E for a detailed examination of percent-encoding concerns for form media types.

When there is no encoding field, the serialization strategy is based on the Encoding Object’s default values:

requestBody:
  content:
    application/x-www-form-urlencoded:
      schema:
        type: object
        properties:
          id:
            type: string
            format: uuid
          address:
            # complex types are stringified to support RFC 1866
            type: object
            properties: {}

With this example, consider an id of f81d4fae-7dec-11d0-a765-00a0c91e6bf6 and a US-style address (with ZIP+4) as follows:

{
  "streetAddress": "123 Example Dr.",
  "city": "Somewhere",
  "state": "CA",
  "zip": "99999+1234"
}

Assuming the most compact representation of the JSON value (with unnecessary whitespace removed), we would expect to see the following request body, where space characters have been replaced with + and +, ", {, and } have been percent-encoded to %2B, %22, %7B, and %7D, respectively:

id=f81d4fae-7dec-11d0-a765-00a0c91e6bf6&address=%7B%22streetAddress%22:%22123+Example+Dr.%22,%22city%22:%22Somewhere%22,%22state%22:%22CA%22,%22zip%22:%2299999%2B1234%22%7D

Note that the id keyword is treated as text/plain per the Encoding Object’s default behavior, and is serialized as-is. If it were treated as application/json, then the serialized value would be a JSON string including quotation marks, which would be percent-encoded as %22.

Here is the id parameter (without address) serialized as application/json instead of text/plain, and then encoded per RFC1866:

id=%22f81d4fae-7dec-11d0-a765-00a0c91e6bf6%22

Note that application/x-www-form-urlencoded is a text format, which requires base64-encoding any binary data:

requestBody:
  content:
    application/x-www-form-urlencoded:
      schema:
        type: object
        properties:
          name:
            type: string
          icon:
            # The default with "contentEncoding" is application/octet-stream,
            # so we need to set image media type(s) in the Encoding Object.
            type: string
            contentEncoding: base64url
  encoding:
    icon:
      contentType: image/png, image/jpeg

Given a name of example and a solid red 2x2-pixel PNG for icon, this would produce a request body of:

name=example&icon=iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAIAAAD91JpzAAAABGdBTUEAALGPC_xhBQAAADhlWElmTU0AKgAAAAgAAYdpAAQAAAABAAAAGgAAAAAAAqACAAQAAAABAAAAAqADAAQAAAABAAAAAgAAAADO0J6QAAAAEElEQVQIHWP8zwACTGCSAQANHQEDqtPptQAAAABJRU5ErkJggg%3D%3D

Note that the = padding characters at the end need to be percent-encoded, even with the “URL safe” contentEncoding: base64url. Some base64-decoding implementations may be able to use the string without the padding per [RFC4648] Section 3.2. However, this is not guaranteed, so it may be more interoperable to keep the padding and rely on percent-decoding.

It is common to use multipart/form-data as a Content-Type when transferring forms as request bodies. In contrast to OpenAPI 2.0, a schema is REQUIRED to define the input parameters to the operation when using multipart content. This supports complex structures as well as supporting mechanisms for multiple file uploads.

The form-data disposition and its name parameter are mandatory for multipart/form-data ([RFC7578] Section 4.2). Array properties are handled by applying the same name to multiple parts, as is recommended by [RFC7578] Section 4.3 for supplying multiple values per form field. See [RFC7578] Section 5 for guidance regarding non-ASCII part names.

Various other multipart types, most notable multipart/mixed ([RFC2046] Section 5.1.3) neither require nor forbid specific Content-Disposition values, which means care must be taken to ensure that any values used are supported by all relevant software. It is not currently possible to correlate schema properties with unnamed, ordered parts in media types such as multipart/mixed, but implementations MAY choose to support such types when Content-Disposition: form-data is used with a name parameter.

Note that there are significant restrictions on what headers can be used with multipart media types in general ([RFC2046] Section 5.1) and multi-part/form-data in particular ([RFC7578] Section 4.8).

Note also that Content-Transfer-Encoding is deprecated for multipart/form-data ([RFC7578] Section 4.7) where binary data is supported, as it is in HTTP.

+Using contentEncoding for a multipart field is equivalent to specifying an Encoding Object with a headers field containing Content-Transfer-Encoding with a schema that requires the value used in contentEncoding. +If contentEncoding is used for a multipart field that has an Encoding Object with a headers field containing Content-Transfer-Encoding with a schema that disallows the value from contentEncoding, the result is undefined for serialization and parsing.

Note that as stated in Working with Binary Data, if the Encoding Object’s contentType, whether set explicitly or implicitly through its default value rules, disagrees with the contentMediaType in a Schema Object, the contentMediaType SHALL be ignored. Because of this, and because the Encoding Object’s contentType defaulting rules do not take the Schema Object’scontentMediaType into account, the use of contentMediaType with an Encoding Object is NOT RECOMMENDED.

See Appendix E for a detailed examination of percent-encoding concerns for form media types.

When the encoding field is not used, the encoding is determined by the Encoding Object’s defaults:

requestBody:
  content:
    multipart/form-data:
      schema:
        type: object
        properties:
          id:
            # default for primitives without a special format is text/plain
            type: string
            format: uuid
          profileImage:
            # default for string with binary format is `application/octet-stream`
            type: string
            format: binary
          addresses:
            # default for arrays is based on the type in the `items`
            # subschema, which is an object, so `application/json`
            type: array
            items:
              $ref: '#/components/schemas/Address'

Using encoding, we can set more specific types for binary data, or non-JSON formats for complex values. We can also describe headers for each part:

requestBody:
  content:
    multipart/form-data:
      schema:
        type: object
        properties:
          id:
            # default is `text/plain`
            type: string
            format: uuid
          addresses:
            # default based on the `items` subschema would be
            # `application/json`, but we want these address objects
            # serialized as `application/xml` instead
            description: addresses in XML format
            type: array
            items:
              $ref: '#/components/schemas/Address'
          profileImage:
            # default is application/octet-stream, but we can declare
            # a more specific image type or types
            type: string
            format: binary
      encoding:
        addresses:
          # require XML Content-Type in utf-8 encoding
          # This is applied to each address part corresponding
          # to each address in he array
          contentType: application/xml; charset=utf-8
        profileImage:
          # only accept png or jpeg
          contentType: image/png, image/jpeg
          headers:
            X-Rate-Limit-Limit:
              description: The number of allowed requests in the current period
              schema:
                type: integer

In accordance with [RFC7578] Section 4.3, multiple files for a single form field are uploaded using the same name (file in this example) for each file’s part:

requestBody:
  content:
    multipart/form-data:
      schema:
        properties:
          # The property name 'file' will be used for all files.
          file:
            type: array
            items: {}

As seen in the Encoding Object’s contentType field documentation, the empty schema for items indicates a media type of application/octet-stream.

A container for the expected responses of an operation. The container maps a HTTP response code to the expected response.

The documentation is not necessarily expected to cover all possible HTTP response codes because they may not be known in advance. However, documentation is expected to cover a successful operation response and any known errors.

The default MAY be used as a default Response Object for all HTTP codes that are not covered individually by the Responses Object.

The Responses Object MUST contain at least one response code, and if only one response code is provided it SHOULD be the response for a successful operation call.

Field Name	Type	Description
default	Response Object \| Reference Object	The documentation of responses other than the ones declared for specific HTTP response codes. Use this field to cover undeclared responses.

Field Pattern	Type	Description
HTTP Status Code	Response Object \| Reference Object	Any HTTP status code can be used as the property name, but only one property per code, to describe the expected response for that HTTP status code. This field MUST be enclosed in quotation marks (for example, “200”) for compatibility between JSON and YAML. To define a range of response codes, this field MAY contain the uppercase wildcard character `X`. For example, `2XX` represents all response codes between `200` and `299`. Only the following range definitions are allowed: `1XX`, `2XX`, `3XX`, `4XX`, and `5XX`. If a response is defined using an explicit code, the explicit code definition takes precedence over the range definition for that code.

This object MAY be extended with Specification Extensions.

A 200 response for a successful operation and a default response for others (implying an error):

{
  "200": {
    "description": "a pet to be returned",
    "content": {
      "application/json": {
        "schema": {
          "$ref": "#/components/schemas/Pet"
        }
      }
    }
  },
  "default": {
    "description": "Unexpected error",
    "content": {
      "application/json": {
        "schema": {
          "$ref": "#/components/schemas/ErrorModel"
        }
      }
    }
  }
}

'200':
  description: a pet to be returned
  content:
    application/json:
      schema:
        $ref: '#/components/schemas/Pet'
default:
  description: Unexpected error
  content:
    application/json:
      schema:
        $ref: '#/components/schemas/ErrorModel'

Describes a single response from an API operation, including design-time, static links to operations based on the response.

Field Name	Type	Description
description	`string`	*REQUIRED. A description of the response. [CommonMark] syntax MAY* be used for rich text representation.
headers	Map[`string`, Header Object \| Reference Object]	Maps a header name to its definition. [RFC7230] Section 3.2 states header names are case insensitive. If a response header is defined with the name `"Content-Type"`, it SHALL be ignored.
content	Map[`string`, Media Type Object]	A map containing descriptions of potential response payloads. The key is a media type or media type range, see [RFC7231] Appendix D, and the value describes it. For responses that match multiple keys, only the most specific key is applicable. e.g. `"text/plain"` overrides `"text/*"`
links	Map[`string`, Link Object \| Reference Object]	A map of operations links that can be followed from the response. The key of the map is a short name for the link, following the naming constraints of the names for Component Objects.

This object MAY be extended with Specification Extensions.

Response of an array of a complex type:

{
  "description": "A complex object array response",
  "content": {
    "application/json": {
      "schema": {
        "type": "array",
        "items": {
          "$ref": "#/components/schemas/VeryComplexType"
        }
      }
    }
  }
}

description: A complex object array response
content:
  application/json:
    schema:
      type: array
      items:
        $ref: '#/components/schemas/VeryComplexType'

Response with a string type:

{
  "description": "A simple string response",
  "content": {
    "text/plain": {
      "schema": {
        "type": "string"
      }
    }
  }
}

description: A simple string response
content:
  text/plain:
    schema:
      type: string

Plain text response with headers:

{
  "description": "A simple string response",
  "content": {
    "text/plain": {
      "schema": {
        "type": "string"
      },
      "example": "whoa!"
    }
  },
  "headers": {
    "X-Rate-Limit-Limit": {
      "description": "The number of allowed requests in the current period",
      "schema": {
        "type": "integer"
      }
    },
    "X-Rate-Limit-Remaining": {
      "description": "The number of remaining requests in the current period",
      "schema": {
        "type": "integer"
      }
    },
    "X-Rate-Limit-Reset": {
      "description": "The number of seconds left in the current period",
      "schema": {
        "type": "integer"
      }
    }
  }
}

description: A simple string response
content:
  text/plain:
    schema:
      type: string
    example: 'whoa!'
headers:
  X-Rate-Limit-Limit:
    description: The number of allowed requests in the current period
    schema:
      type: integer
  X-Rate-Limit-Remaining:
    description: The number of remaining requests in the current period
    schema:
      type: integer
  X-Rate-Limit-Reset:
    description: The number of seconds left in the current period
    schema:
      type: integer

Response with no return value:

{
  "description": "object created"
}

description: object created

A map of possible out-of band callbacks related to the parent operation. Each value in the map is a Path Item Object that describes a set of requests that may be initiated by the API provider and the expected responses. The key value used to identify the Path Item Object is an expression, evaluated at runtime, that identifies a URL to use for the callback operation.

To describe incoming requests from the API provider independent from another API call, use the webhooks field.

Field Pattern	Type	Description
{expression}	Path Item Object	A Path Item Object used to define a callback request and expected responses. A complete example is available.

This object MAY be extended with Specification Extensions.

The key that identifies the Path Item Object is a runtime expression that can be evaluated in the context of a runtime HTTP request/response to identify the URL to be used for the callback request. A simple example might be $request.body#/url. However, using a runtime expression the complete HTTP message can be accessed. This includes accessing any part of a body that a JSON Pointer [RFC6901] can reference.

For example, given the following HTTP request:

POST /subscribe/myevent?queryUrl=https://clientdomain.com/stillrunning HTTP/1.1
Host: example.org
Content-Type: application/json
Content-Length: 188

{
  "failedUrl": "https://clientdomain.com/failed",
  "successUrls": [
    "https://clientdomain.com/fast",
    "https://clientdomain.com/medium",
    "https://clientdomain.com/slow"
  ]
}

resulting in:

201 Created
Location: https://example.org/subscription/1

The following examples show how the various expressions evaluate, assuming the callback operation has a path parameter named eventType and a query parameter named queryUrl.

Expression	Value
$url	https://example.org/subscribe/myevent?queryUrl=https://clientdomain.com/stillrunning
$method	POST
$request.path.eventType	myevent
$request.query.queryUrl	https://clientdomain.com/stillrunning
$request.header.content-type	application/json
$request.body#/failedUrl	https://clientdomain.com/failed
$request.body#/successUrls/1	https://clientdomain.com/medium
$response.header.Location	https://example.org/subscription/1

The following example uses the user provided queryUrl query string parameter to define the callback URL. This is similar to a webhook, but differs in that the callback only occurs because of the initial request that sent the queryUrl.

myCallback:
  '{$request.query.queryUrl}':
    post:
      requestBody:
        description: Callback payload
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SomePayload'
      responses:
        '200':
          description: callback successfully processed

The following example shows a callback where the server is hard-coded, but the query string parameters are populated from the id and email property in the request body.

transactionCallback:
  'http://notificationServer.com?transactionId={$request.body#/id}&email={$request.body#/email}':
    post:
      requestBody:
        description: Callback payload
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SomePayload'
      responses:
        '200':
          description: callback successfully processed

An object grouping an internal or external example value with basic summary and description metadata. This object is typically used in fields named examples (plural), and is a referenceable alternative to older example (singular) fields that do not support referencing or metadata.

Examples allow demonstration of the usage of properties, parameters and objects within OpenAPI.

Field Name	Type	Description
summary	`string`	Short description for the example.
description	`string`	Long description for the example. [CommonMark] syntax MAY be used for rich text representation.
value	Any	Embedded literal example. The `value` field and `externalValue` field are mutually exclusive. To represent examples of media types that cannot naturally represented in JSON or YAML, use a string value to contain the example, escaping where necessary.
externalValue	`string`	A URI that identifies the literal example. This provides the capability to reference examples that cannot easily be included in JSON or YAML documents. The `value` field and `externalValue` field are mutually exclusive. See the rules for resolving Relative References.

This object MAY be extended with Specification Extensions.

In all cases, the example value SHOULD be compatible with the schema of its associated value. Tooling implementations MAY choose to validate compatibility automatically, and reject the example value(s) if incompatible.

Example Objects can be used in both Parameter Objects and Media Type Objects. In both Objects, this is done through the examples (plural) field. However, there are several other ways to provide examples: The example (singular) field that is mutually exclusive with examples in both Objects, and two keywords (the deprecated singular example and the current plural examples, which takes an array of examples) in the Schema Object that appears in the schema field of both Objects. Each of these fields has slightly different considerations.

The Schema Object’s fields are used to show example values without regard to how they might be formatted as parameters or within media type representations. The examples array is part of JSON Schema and is the preferred way to include examples in the Schema Object, while example is retained purely for compatibility with older versions of the OpenAPI Specification.

The mutually exclusive fields in the Parameter or Media Type Objects are used to show example values which SHOULD both match the schema and be formatted as they would appear as a serialized parameter or within a media type representation. The exact serialization and encoding is determined by various fields in the Parameter Object, or in the Media Type Object’s Encoding Object. Because examples using these fields represent the final serialized form of the data, they SHALL override any example in the corresponding Schema Object.

The singular example field in the Parameter or Media Type Object is concise and convenient for simple examples, but does not offer any other advantages over using Example Objects under examples.

Some examples cannot be represented directly in JSON or YAML. For all three ways of providing examples, these can be shown as string values with any escaping necessary to make the string valid in the JSON or YAML format of documents that comprise the OpenAPI Description. With the Example Object, such values can alternatively be handled through the externalValue field.

In a request body:

requestBody:
  content:
    'application/json':
      schema:
        $ref: '#/components/schemas/Address'
      examples:
        foo:
          summary: A foo example
          value:
            foo: bar
        bar:
          summary: A bar example
          value:
            bar: baz
    application/xml:
      examples:
        xmlExample:
          summary: This is an example in XML
          externalValue: https://example.org/examples/address-example.xml
    text/plain:
      examples:
        textExample:
          summary: This is a text example
          externalValue: https://foo.bar/examples/address-example.txt

In a parameter:

parameters:
  - name: zipCode
    in: query
    schema:
      type: string
      format: zip-code
    examples:
      zip-example:
        $ref: '#/components/examples/zip-example'

In a response:

responses:
  '200':
    description: your car appointment has been booked
    content:
      application/json:
        schema:
          $ref: '#/components/schemas/SuccessResponse'
        examples:
          confirmation-success:
            $ref: '#/components/examples/confirmation-success'

Two different uses of JSON strings:

First, a request or response body that is just a JSON string (not an object containing a string):

"application/json": {
  "schema": {
    "type": "string"
  },
  "examples": {
    "jsonBody": {
      "description": "A body of just the JSON string \"json\"",
      "value": "json"
    }
  }
}

application/json:
  schema:
    type: string
  examples:
    jsonBody:
      description: 'A body of just the JSON string "json"'
      value: json

In the above example, we can just show the JSON string (or any JSON value) as-is, rather than stuffing a serialized JSON value into a JSON string, which would have looked like "\"json\"".

In contrast, a JSON string encoded inside of a URL-style form body:

"application/x-www-form-urlencoded": {
  "schema": {
    "type": "object",
    "properties": {
      "jsonValue": {
        "type": "string"
      }
    }
  },
  "encoding": {
    "jsonValue": {
      "contentType": "application/json"
    }
  },
  "examples": {
    "jsonFormValue": {
      "description": "The JSON string \"json\" as a form value",
      "value": "jsonValue=%22json%22"
    }
  }
}

application/x-www-form-urlencoded:
  schema:
    type: object
    properties:
      jsonValue:
        type: string
  encoding:
    jsonValue:
      contentType: application/json
  examples:
    jsonFormValue:
      description: 'The JSON string "json" as a form value'
      value: jsonValue=%22json%22

In this example, the JSON string had to be serialized before encoding it into the URL form value, so the example includes the quotation marks that are part of the JSON serialization, which are then URL percent-encoded.

The Link Object represents a possible design-time link for a response. The presence of a link does not guarantee the caller’s ability to successfully invoke it, rather it provides a known relationship and traversal mechanism between responses and other operations.

Unlike dynamic links (i.e. links provided in the response payload), the OAS linking mechanism does not require link information in the runtime response.

For computing links and providing instructions to execute them, a runtime expression is used for accessing values in an operation and using them as parameters while invoking the linked operation.

Field Name	Type	Description
operationRef	`string`	A URI reference to an OAS operation. This field is mutually exclusive of the `operationId` field, and MUST point to an Operation Object. Relative `operationRef` values MAY be used to locate an existing Operation Object in the OpenAPI Description.
operationId	`string`	The name of an existing, resolvable OAS operation, as defined with a unique `operationId`. This field is mutually exclusive of the `operationRef` field.
parameters	Map[`string`, Any \| {expression}]	A map representing parameters to pass to an operation as specified with `operationId` or identified via `operationRef`. The key is the parameter name to be used (optionally qualified with the parameter location, e.g. `path.id` for an `id` parameter in the path), whereas the value can be a constant or an expression to be evaluated and passed to the linked operation.
requestBody	Any \| {expression}	A literal value or {expression} to use as a request body when calling the target operation.
description	`string`	A description of the link. [CommonMark] syntax MAY be used for rich text representation.
server	Server Object	A server object to be used by the target operation.

This object MAY be extended with Specification Extensions.

A linked operation MUST be identified using either an operationRef or operationId. The identified or reference operation MUST be unique, and in the case of an operationId, it MUST be resolved within the scope of the OpenAPI Description (OAD). Because of the potential for name clashes, the operationRef syntax is preferred for multi-document OADs. However, because use of an operation depends on its URL path template in the Paths Object, operations from any Path Item Object that is referenced multiple times within the OAD cannot be resolved unambiguously. In such ambiguous cases, the resulting behavior is implementation-defined and MAY result in an error.

Note that it is not possible to provide a constant value to parameters that matches the syntax of a runtime expression. It is possible to have ambiguous parameter names, e.g. name: "id", in: "path" and name: "path.id", in: "query"; this is NOT RECOMMENDED and the behavior is implementation-defined, however implementations SHOULD prefer the qualified interpretation (path.id as a path parameter), as the names can always be qualified to disambiguate them (e.g. using query.path.id for the query parameter).

Computing a link from a request operation where the $request.path.id is used to pass a request parameter to the linked operation.

paths:
  /users/{id}:
    parameters:
      - name: id
        in: path
        required: true
        description: the user identifier, as userId
        schema:
          type: string
    get:
      responses:
        '200':
          description: the user being returned
          content:
            application/json:
              schema:
                type: object
                properties:
                  uuid: # the unique user id
                    type: string
                    format: uuid
          links:
            address:
              # the target link operationId
              operationId: getUserAddress
              parameters:
                # get the `id` field from the request path parameter named `id`
                userid: $request.path.id
  # the path item of the linked operation
  /users/{userid}/address:
    parameters:
      - name: userid
        in: path
        required: true
        description: the user identifier, as userId
        schema:
          type: string
    # linked operation
    get:
      operationId: getUserAddress
      responses:
        '200':
          description: the user's address

When a runtime expression fails to evaluate, no parameter value is passed to the target operation.

Values from the response body can be used to drive a linked operation.

links:
  address:
    operationId: getUserAddressByUUID
    parameters:
      # get the `uuid` field from the `uuid` field in the response body
      userUuid: $response.body#/uuid

Clients follow all links at their discretion. Neither permissions nor the capability to make a successful call to that link is guaranteed solely by the existence of a relationship.

As references to operationId MAY NOT be possible (the operationId is an optional field in an Operation Object), references MAY also be made through a relative operationRef:

links:
  UserRepositories:
    # returns array of '#/components/schemas/repository'
    operationRef: '#/paths/~12.0~1repositories~1%7Busername%7D/get'
    parameters:
      username: $response.body#/username

or a URI operationRef:

links:
  UserRepositories:
    # returns array of '#/components/schemas/repository'
    operationRef: https://na2.gigantic-server.com/#/paths/~12.0~1repositories~1%7Busername%7D/get
    parameters:
      username: $response.body#/username

Note that in the use of operationRef the escaped forward-slash is necessary when using JSON Pointer, and it is necessary to URL-encode { and } as %7B and %7D, respectively, when using JSON Pointer as URI fragments.

Runtime expressions allow defining values based on information that will only be available within the HTTP message in an actual API call. This mechanism is used by Link Objects and Callback Objects.

The runtime expression is defined by the following [ABNF] syntax

    expression = "$url" / "$method" / "$statusCode" / "$request." source / "$response." source
    source     = header-reference / query-reference / path-reference / body-reference
    header-reference = "header." token
    query-reference  = "query." name
    path-reference   = "path." name
    body-reference   = "body" ["#" json-pointer ]
    json-pointer    = *( "/" reference-token )
    reference-token = *( unescaped / escaped )
    unescaped       = %x00-2E / %x30-7D / %x7F-10FFFF
                    ; %x2F ('/') and %x7E ('~') are excluded from 'unescaped'
    escaped         = "~" ( "0" / "1" )
                    ; representing '~' and '/', respectively
    name = *( CHAR )
    token = 1*tchar
    tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "."
          / "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA

Here, json-pointer is taken from [RFC6901], char from [RFC7159] Section 7 and token from [RFC7230] Section 3.2.6.

The name identifier is case-sensitive, whereas token is not.

The table below provides examples of runtime expressions and examples of their use in a value:

Source Location	example expression	notes
HTTP Method	`$method`	The allowable values for the `$method` will be those for the HTTP operation.
Requested media type	`$request.header.accept`
Request parameter	`$request.path.id`	Request parameters MUST be declared in the `parameters` section of the parent operation or they cannot be evaluated. This includes request headers.
Request body property	`$request.body#/user/uuid`	In operations which accept payloads, references may be made to portions of the `requestBody` or the entire body.
Request URL	`$url`
Response value	`$response.body#/status`	In operations which return payloads, references may be made to portions of the response body or the entire body.
Response header	`$response.header.Server`	Single header values only are available

Runtime expressions preserve the type of the referenced value. Expressions can be embedded into string values by surrounding the expression with {} curly braces.

Describes a single header for HTTP responses and for individual parts in multipart representations; see the relevant Response Object and Encoding Object documentation for restrictions on which headers can be described.

The Header Object follows the structure of the Parameter Object, including determining its serialization strategy based on whether schema or content is present, with the following changes:

name MUST NOT be specified, it is given in the corresponding headers map.
in MUST NOT be specified, it is implicitly in header.
All traits that are affected by the location MUST be applicable to a location of header (for example, style). This means that allowEmptyValue and allowReserved MUST NOT be used, and style, if used, MUST be limited to "simple".

These fields MAY be used with either content or schema.

Field Name	Type	Description
description	`string`	A brief description of the header. This could contain examples of use. [CommonMark] syntax MAY be used for rich text representation.
required	`boolean`	Determines whether this header is mandatory. The default value is `false`.
deprecated	`boolean`	Specifies that the header is deprecated and SHOULD be transitioned out of usage. Default value is `false`.

This object MAY be extended with Specification Extensions.

For simpler scenarios, a schema and style can describe the structure and syntax of the header. When example or examples are provided in conjunction with the schema field, the example MUST follow the prescribed serialization strategy for the header.

Serializing with schema is NOT RECOMMENDED for headers with parameters (name=value pairs following a ;) in their values, or where values might have non-URL-safe characters; see Appendix D for details.

When example or examples are provided in conjunction with the schema field, the example SHOULD match the specified schema and follow the prescribed serialization strategy for the header. The example and examples fields are mutually exclusive, and if either is present it SHALL override any example in the schema.

Field Name	Type	Description
style	`string`	Describes how the header value will be serialized. The default (and only legal value for headers) is `"simple"`.
explode	`boolean`	When this is true, header values of type `array` or `object` generate a single header whose value is a comma-separated list of the array items or key-value pairs of the map, see Style Examples. For other data types this field has no effect. The default value is `false`.
schema	Schema Object \| Reference Object	The schema defining the type used for the header.
example	Any	Example of the header’s potential value; see Working With Examples.
examples	Map[ `string`, Example Object \| Reference Object]	Examples of the header’s potential value; see Working With Examples.

See also Appendix C: Using RFC6570-Based Serialization for additional guidance.

For more complex scenarios, the content field can define the media type and schema of the header, as well as give examples of its use. Using content with a text/plain media type is RECOMMENDED for headers where the schema strategy is not appropriate.

Field Name	Type	Description
content	Map[`string`, Media Type Object]	A map containing the representations for the header. The key is the media type and the value describes it. The map MUST only contain one entry.

A simple header of type integer:

"X-Rate-Limit-Limit": {
  "description": "The number of allowed requests in the current period",
  "schema": {
    "type": "integer"
  }
}

X-Rate-Limit-Limit:
  description: The number of allowed requests in the current period
  schema:
    type: integer

Requiring that a strong ETag header (with a value starting with " rather than W/) is present. Note the use of content, because using schema and style would require the " to be percent-encoded as %22:

"ETag": {
  "required": true,
  "content": {
    "text/plain": {
      "schema": {
        "type": "string",
        "pattern": "^\""
      }
    }
  }
}

ETag:
  required: true
  content:
    text/plain:
      schema:
        type: string
        pattern: ^"

Adds metadata to a single tag that is used by the Operation Object. It is not mandatory to have a Tag Object per tag defined in the Operation Object instances.

Field Name	Type	Description
name	`string`	*REQUIRED*. The name of the tag.
description	`string`	A description for the tag. [CommonMark] syntax MAY be used for rich text representation.
externalDocs	External Documentation Object	Additional external documentation for this tag.

This object MAY be extended with Specification Extensions.

{
  "name": "pet",
  "description": "Pets operations"
}

name: pet
description: Pets operations

A simple object to allow referencing other components in the OpenAPI Description, internally and externally.

The $ref string value contains a URI [RFC3986], which identifies the value being referenced.

See the rules for resolving Relative References.

Field Name	Type	Description
$ref	`string`	*REQUIRED. The reference identifier. This MUST* be in the form of a URI.
summary	`string`	A short summary which by default SHOULD override that of the referenced component. If the referenced object-type does not allow a `summary` field, then this field has no effect.
description	`string`	A description which by default SHOULD override that of the referenced component. [CommonMark] syntax MAY be used for rich text representation. If the referenced object-type does not allow a `description` field, then this field has no effect.

This object cannot be extended with additional properties, and any properties added SHALL be ignored.

Note that this restriction on additional properties is a difference between Reference Objects and Schema Objects that contain a $ref keyword.

{
  "$ref": "#/components/schemas/Pet"
}

$ref: '#/components/schemas/Pet'

{
  "$ref": "Pet.json"
}

$ref: Pet.yaml

{
  "$ref": "definitions.json#/Pet"
}

$ref: definitions.yaml#/Pet

The Schema Object allows the definition of input and output data types. These types can be objects, but also primitives and arrays. This object is a superset of the JSON Schema Specification Draft 2020-12. The empty schema (which allows any instance to validate) MAY be represented by the boolean value true and a schema which allows no instance to validate MAY be represented by the boolean value false.

For more information about the keywords, see JSON Schema Core and JSON Schema Validation.

Unless stated otherwise, the keyword definitions follow those of JSON Schema and do not add any additional semantics; this includes keywords such as $schema, $id, $ref, and $dynamicRef being URIs rather than URLs. Where JSON Schema indicates that behavior is defined by the application (e.g. for annotations), OAS also defers the definition of semantics to the application consuming the OpenAPI document.

The OpenAPI Schema Object dialect is defined as requiring the OAS base vocabulary, in addition to the vocabularies as specified in the JSON Schema Specification Draft 2020-12 general purpose meta-schema.

The OpenAPI Schema Object dialect for this version of the specification is identified by the URI https://spec.openapis.org/oas/3.1/dialect/base (the “OAS dialect schema id”).

The following keywords are taken from the JSON Schema specification but their definitions have been extended by the OAS:

description - [CommonMark] syntax MAY be used for rich text representation.
format - See Data Type Formats for further details. While relying on JSON Schema’s defined formats, the OAS offers a few additional predefined formats.

In addition to the JSON Schema keywords comprising the OAS dialect, the Schema Object supports keywords from any other vocabularies, or entirely arbitrary properties.

JSON Schema implementations MAY choose to treat keywords defined by the OpenAPI Specification’s base vocabulary as unknown keywords, due to its inclusion in the OAS dialect with a $vocabulary value of false. The OAS base vocabulary is comprised of the following keywords:

Field Name	Type	Description
discriminator	Discriminator Object	Adds support for polymorphism. The discriminator is used to determine which of a set of schemas a payload is expected to satisfy. See Composition and Inheritance for more details.
xml	XML Object	This MAY be used only on property schemas. It has no effect on root schemas. Adds additional metadata to describe the XML representation of this property.
externalDocs	External Documentation Object	Additional external documentation for this schema.
example	Any	A free-form field to include an example of an instance for this schema. To represent examples that cannot be naturally represented in JSON or YAML, a string value can be used to contain the example with escaping where necessary. Deprecated: The `example` field has been deprecated in favor of the JSON Schema `examples` keyword. Use of `example` is discouraged, and later versions of this specification may remove it.

This object MAY be extended with Specification Extensions, though as noted, additional properties MAY omit the x- prefix within this object.

JSON Schema Draft 2020-12 supports collecting annotations, including treating unrecognized keywords as annotations. OAS implementations MAY use such annotations, including extensions not recognized as part of a declared JSON Schema vocabulary, as the basis for further validation. Note that JSON Schema Draft 2020-12 does not require an x- prefix for extensions.

The format keyword (when using default format-annotation vocabulary) and the contentMediaType, contentEncoding, and contentSchema keywords define constraints on the data, but are treated as annotations instead of being validated directly. Extended validation is one way that these constraints MAY be enforced.

The readOnly and writeOnly keywords are annotations, as JSON Schema is not aware of how the data it is validating is being used. Validation of these keywords MAY be done by checking the annotation, the read or write direction, and (if relevant) the current value of the field. JSON Schema Validation Draft 2020-12 §9.4 defines the expectations of these keywords, including that a resource (described as the “owning authority”) MAY either ignore a readOnly field or treat it as an error.

Fields that are both required and read-only are an example of when it is beneficial to ignore a readOnly: true constraint in a PUT, particularly if the value has not been changed. This allows correctly requiring the field on a GET and still using the same representation and schema with PUT. Even when read-only fields are not required, stripping them is burdensome for clients, particularly when the JSON data is complex or deeply nested.

Note that the behavior of readOnly in particular differs from that specified by version 3.0 of this specification.

The OpenAPI Specification allows combining and extending model definitions using the allOf keyword of JSON Schema, in effect offering model composition. allOf takes an array of object definitions that are validated independently but together compose a single object.

While composition offers model extensibility, it does not imply a hierarchy between the models. To support polymorphism, the OpenAPI Specification adds the discriminator field. When used, the discriminator indicates the name of the property that hints which schema definition is expected to validate the structure of the model. As such, the discriminator field MUST be a required field. There are two ways to define the value of a discriminator for an inheriting instance.

Use the schema name.
Override the schema name by overriding the property with a new value. If a new value exists, this takes precedence over the schema name.

Implementations MAY support defining generic or template data structures using JSON Schema’s dynamic referencing feature:

$dynamicAnchor identifies a set of possible schemas (including a default placeholder schema) to which a $dynamicRef can resolve
$dynamicRef resolves to the first matching $dynamicAnchor encountered on its path from the schema entry point to the reference, as described in the JSON Schema specification

An example is included in the “Schema Object Examples” section below, and further information can be found on the Learn OpenAPI site’s “Dynamic References” page.

The Schema Object’s enum keyword does not allow associating descriptions or other information with individual values.

Implementations MAY support recognizing a oneOf or anyOf where each subschema in the keyword’s array consists of a const keyword and annotations such as title or description as an enumerated type with additional information. The exact behavior of this pattern beyond what is required by JSON Schema is implementation-defined.

The xml field allows extra definitions when translating the JSON definition to XML. The XML Object contains additional information about the available options.

It is important for tooling to be able to determine which dialect or meta-schema any given resource wishes to be processed with: JSON Schema Core, JSON Schema Validation, OpenAPI Schema dialect, or some custom meta-schema.

The $schema keyword MAY be present in any Schema Object that is a schema resource root, and if present MUST be used to determine which dialect should be used when processing the schema. This allows use of Schema Objects which comply with other drafts of JSON Schema than the default Draft 2020-12 support. Tooling MUST support the OAS dialect schema id, and MAY support additional values of $schema.

To allow use of a different default $schema value for all Schema Objects contained within an OAS document, a jsonSchemaDialect value may be set within the OpenAPI Object. If this default is not set, then the OAS dialect schema id MUST be used for these Schema Objects. The value of $schema within a resource root Schema Object always overrides any default.

For standalone JSON Schema documents that do not set $schema, or for Schema Objects in OpenAPI description documents that are not complete documents, the dialect SHOULD be assumed to be the OAS dialect. However, for maximum interoperability, it is RECOMMENDED that OpenAPI description authors explicitly set the dialect through $schema in such documents.

{
  "type": "string",
  "format": "email"
}

type: string
format: email

{
  "type": "object",
  "required": ["name"],
  "properties": {
    "name": {
      "type": "string"
    },
    "address": {
      "$ref": "#/components/schemas/Address"
    },
    "age": {
      "type": "integer",
      "format": "int32",
      "minimum": 0
    }
  }
}

type: object
required:
  - name
properties:
  name:
    type: string
  address:
    $ref: '#/components/schemas/Address'
  age:
    type: integer
    format: int32
    minimum: 0

For a simple string to string mapping:

{
  "type": "object",
  "additionalProperties": {
    "type": "string"
  }
}

type: object
additionalProperties:
  type: string

For a string to model mapping:

{
  "type": "object",
  "additionalProperties": {
    "$ref": "#/components/schemas/ComplexModel"
  }
}

type: object
additionalProperties:
  $ref: '#/components/schemas/ComplexModel'

{
  "oneOf": [
    {
      "const": "RGB",
      "title": "Red, Green, Blue",
      "description": "Specify colors with the red, green, and blue additive color model"
    },
    {
      "const": "CMYK",
      "title": "Cyan, Magenta, Yellow, Black",
      "description": "Specify colors with the cyan, magenta, yellow, and black subtractive color model"
    }
  ]
}

oneOf:
  - const: RGB
    title: Red, Green, Blue
    description: Specify colors with the red, green, and blue additive color model
  - const: CMYK
    title: Cyan, Magenta, Yellow, Black
    description: Specify colors with the cyan, magenta, yellow, and black subtractive color model

{
  "type": "object",
  "properties": {
    "id": {
      "type": "integer",
      "format": "int64"
    },
    "name": {
      "type": "string"
    }
  },
  "required": ["name"],
  "examples": [
    {
      "name": "Puma",
      "id": 1
    }
  ]
}

type: object
properties:
  id:
    type: integer
    format: int64
  name:
    type: string
required:
  - name
examples:
  - name: Puma
    id: 1

{
  "components": {
    "schemas": {
      "ErrorModel": {
        "type": "object",
        "required": ["message", "code"],
        "properties": {
          "message": {
            "type": "string"
          },
          "code": {
            "type": "integer",
            "minimum": 100,
            "maximum": 600
          }
        }
      },
      "ExtendedErrorModel": {
        "allOf": [
          {
            "$ref": "#/components/schemas/ErrorModel"
          },
          {
            "type": "object",
            "required": ["rootCause"],
            "properties": {
              "rootCause": {
                "type": "string"
              }
            }
          }
        ]
      }
    }
  }
}

components:
  schemas:
    ErrorModel:
      type: object
      required:
        - message
        - code
      properties:
        message:
          type: string
        code:
          type: integer
          minimum: 100
          maximum: 600
    ExtendedErrorModel:
      allOf:
        - $ref: '#/components/schemas/ErrorModel'
        - type: object
          required:
            - rootCause
          properties:
            rootCause:
              type: string

{
  "components": {
    "schemas": {
      "Pet": {
        "type": "object",
        "discriminator": {
          "propertyName": "petType"
        },
        "properties": {
          "name": {
            "type": "string"
          },
          "petType": {
            "type": "string"
          }
        },
        "required": ["name", "petType"]
      },
      "Cat": {
        "description": "A representation of a cat. Note that `Cat` will be used as the discriminating value.",
        "allOf": [
          {
            "$ref": "#/components/schemas/Pet"
          },
          {
            "type": "object",
            "properties": {
              "huntingSkill": {
                "type": "string",
                "description": "The measured skill for hunting",
                "default": "lazy",
                "enum": ["clueless", "lazy", "adventurous", "aggressive"]
              }
            },
            "required": ["huntingSkill"]
          }
        ]
      },
      "Dog": {
        "description": "A representation of a dog. Note that `Dog` will be used as the discriminating value.",
        "allOf": [
          {
            "$ref": "#/components/schemas/Pet"
          },
          {
            "type": "object",
            "properties": {
              "packSize": {
                "type": "integer",
                "format": "int32",
                "description": "the size of the pack the dog is from",
                "default": 0,
                "minimum": 0
              }
            },
            "required": ["packSize"]
          }
        ]
      }
    }
  }
}

components:
  schemas:
    Pet:
      type: object
      discriminator:
        propertyName: petType
      properties:
        name:
          type: string
        petType:
          type: string
      required:
        - name
        - petType
    Cat: # "Cat" will be used as the discriminating value
      description: A representation of a cat
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          properties:
            huntingSkill:
              type: string
              description: The measured skill for hunting
              enum:
                - clueless
                - lazy
                - adventurous
                - aggressive
          required:
            - huntingSkill
    Dog: # "Dog" will be used as the discriminating value
      description: A representation of a dog
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          properties:
            packSize:
              type: integer
              format: int32
              description: the size of the pack the dog is from
              default: 0
              minimum: 0
          required:
            - packSize

{
  "components": {
    "schemas": {
      "genericArrayComponent": {
        "$id": "fully_generic_array",
        "type": "array",
        "items": {
          "$dynamicRef": "#generic-array"
        },
        "$defs": {
          "allowAll": {
            "$dynamicAnchor": "generic-array"
          }
        }
      },
      "numberArray": {
        "$id": "array_of_numbers",
        "$ref": "fully_generic_array",
        "$defs": {
          "numbersOnly": {
            "$dynamicAnchor": "generic-array",
            "type": "number"
          }
        }
      },
      "stringArray": {
        "$id": "array_of_strings",
        "$ref": "fully_generic_array",
        "$defs": {
          "stringsOnly": {
            "$dynamicAnchor": "generic-array",
            "type": "string"
          }
        }
      },
      "objWithTypedArray": {
        "$id": "obj_with_typed_array",
        "type": "object",
        "required": ["dataType", "data"],
        "properties": {
          "dataType": {
            "enum": ["string", "number"]
          }
        },
        "oneOf": [{
          "properties": {
            "dataType": {"const": "string"},
            "data": {"$ref": "array_of_strings"}
          }
        }, {
          "properties": {
            "dataType": {"const": "number"},
            "data": {"$ref": "array_of_numbers"}
          }
        }]
      }
    }
  }
}

components:
  schemas:
    genericArrayComponent:
      $id: fully_generic_array
      type: array
      items:
        $dynamicRef: '#generic-array'
      $defs:
        allowAll:
          $dynamicAnchor: generic-array
    numberArray:
      $id: array_of_numbers
      $ref: fully_generic_array
      $defs:
        numbersOnly:
          $dynamicAnchor: generic-array
          type: number
    stringArray:
      $id: array_of_strings
      $ref: fully_generic_array
      $defs:
        stringsOnly:
          $dynamicAnchor: generic-array
          type: string
    objWithTypedArray:
      $id: obj_with_typed_array
      type: object
      required:
      - dataType
      - data
      properties:
        dataType:
          enum:
          - string
          - number
      oneOf:
      - properties:
          dataType:
            const: string
          data:
            $ref: array_of_strings
      - properties:
          dataType:
            const: number
          data:
            $ref: array_of_numbers

When request bodies or response payloads may be one of a number of different schemas, a Discriminator Object gives a hint about the expected schema of the document. This hint can be used to aid in serialization, deserialization, and validation. The Discriminator Object does this by implicitly or explicitly associating the possible values of a named property with alternative schemas.

Note that discriminator MUST NOT change the validation outcome of the schema.

Field Name	Type	Description
propertyName	`string`	*REQUIRED. The name of the property in the payload that will hold the discriminating value. This property SHOULD* be required in the payload schema, as the behavior when the property is absent is undefined.
mapping	Map[`string`, `string`]	An object to hold mappings between payload values and schema names or URI references.

This object MAY be extended with Specification Extensions.

The Discriminator Object is legal only when using one of the composite keywords oneOf, anyOf, allOf.

In both the oneOf and anyOf use cases, where those keywords are adjacent to discriminator, all possible schemas MUST be listed explicitly.

To avoid redundancy, the discriminator MAY be added to a parent schema definition, and all schemas building on the parent schema via an allOf construct may be used as an alternate schema.

The allOf form of discriminator is only useful for non-validation use cases; validation with the parent schema with this form of discriminator does not perform a search for child schemas or use them in validation in any way. This is because discriminator cannot change the validation outcome, and no standard JSON Schema keyword connects the parent schema to the child schemas.

The behavior of any configuration of oneOf, anyOf, allOf and discriminator that is not described above is undefined.

The value of the property named in propertyName is used as the name of the associated schema under the Components Object, unless a mapping is present for that value. The mapping entry maps a specific property value to either a different schema component name, or to a schema identified by a URI. When using implicit or explicit schema component names, inline oneOf or anyOf subschemas are not considered. The behavior of a mapping value that is both a valid schema name and a valid relative URI reference is implementation-defined, but it is RECOMMENDED that it be treated as a schema name. To ensure that an ambiguous value (e.g. "foo") is treated as a relative URI reference by all implementations, authors MUST prefix it with the "." path segment (e.g. "./foo").

Mapping keys MUST be string values, but tooling MAY convert response values to strings for comparison. However, the exact nature of such conversions are implementation-defined.

For these examples, assume all schemas are in the entry document of the OAD; for handling of discriminator in referenced documents see Resolving Implicit Connections.

In OAS 3.x, a response payload MAY be described to be exactly one of any number of types:

MyResponseType:
  oneOf:
    - $ref: '#/components/schemas/Cat'
    - $ref: '#/components/schemas/Dog'
    - $ref: '#/components/schemas/Lizard'

which means the payload MUST, by validation, match exactly one of the schemas described by Cat, Dog, or Lizard. Deserialization of a oneOf can be a costly operation, as it requires determining which schema matches the payload and thus should be used in deserialization. This problem also exists for anyOf schemas. A discriminator MAY be used as a “hint” to improve the efficiency of selection of the matching schema. The discriminator field cannot change the validation result of the oneOf, it can only help make the deserialization more efficient and provide better error messaging. We can specify the exact field that tells us which schema is expected to match the instance:

MyResponseType:
  oneOf:
    - $ref: '#/components/schemas/Cat'
    - $ref: '#/components/schemas/Dog'
    - $ref: '#/components/schemas/Lizard'
  discriminator:
    propertyName: petType

The expectation now is that a property with name petType MUST be present in the response payload, and the value will correspond to the name of a schema defined in the OpenAPI Description. Thus the response payload:

{
  "id": 12345,
  "petType": "Cat"
}

will indicate that the Cat schema is expected to match this payload.

In scenarios where the value of the discriminator field does not match the schema name or implicit mapping is not possible, an optional mapping definition MAY be used:

MyResponseType:
  oneOf:
    - $ref: '#/components/schemas/Cat'
    - $ref: '#/components/schemas/Dog'
    - $ref: '#/components/schemas/Lizard'
    - $ref: https://gigantic-server.com/schemas/Monster/schema.json
  discriminator:
    propertyName: petType
    mapping:
      dog: '#/components/schemas/Dog'
      monster: https://gigantic-server.com/schemas/Monster/schema.json

Here the discriminating value of dog will map to the schema #/components/schemas/Dog, rather than the default (implicit) value of #/components/schemas/dog. If the discriminating value does not match an implicit or explicit mapping, no schema can be determined and validation SHOULD fail.

When used in conjunction with the anyOf construct, the use of the discriminator can avoid ambiguity for serializers/deserializers where multiple schemas may satisfy a single payload.

This example shows the allOf usage, which avoids needing to reference all child schemas in the parent:

components:
  schemas:
    Pet:
      type: object
      required:
        - petType
      properties:
        petType:
          type: string
      discriminator:
        propertyName: petType
        mapping:
          dog: Dog
    Cat:
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          # all other properties specific to a `Cat`
          properties:
            name:
              type: string
    Dog:
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          # all other properties specific to a `Dog`
          properties:
            bark:
              type: string
    Lizard:
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          # all other properties specific to a `Lizard`
          properties:
            lovesRocks:
              type: boolean

Validated against the Pet schema, a payload like this:

{
  "petType": "Cat",
  "name": "Misty"
}

will indicate that the #/components/schemas/Cat schema is expected to match. Likewise this payload:

{
  "petType": "dog",
  "bark": "soft"
}

will map to #/components/schemas/Dog because the dog entry in the mapping element maps to Dog which is the schema name for #/components/schemas/Dog.

A metadata object that allows for more fine-tuned XML model definitions.

When using arrays, XML element names are not inferred (for singular/plural forms) and the name field SHOULD be used to add that information. See examples for expected behavior.

Field Name	Type	Description
name	`string`	Replaces the name of the element/attribute used for the described schema property. When defined within `items`, it will affect the name of the individual XML elements within the list. When defined alongside `type` being `"array"` (outside the `items`), it will affect the wrapping element if and only if `wrapped` is `true`. If `wrapped` is `false`, it will be ignored.
namespace	`string`	The URI of the namespace definition. Value MUST be in the form of a non-relative URI.
prefix	`string`	The prefix to be used for the name.
attribute	`boolean`	Declares whether the property definition translates to an attribute instead of an element. Default value is `false`.
wrapped	`boolean`	MAY be used only for an array definition. Signifies whether the array is wrapped (for example, `<books><book/><book/></books>`) or unwrapped (`<book/><book/>`). Default value is `false`. The definition takes effect only when defined alongside `type` being `"array"` (outside the `items`).

This object MAY be extended with Specification Extensions.

The namespace field is intended to match the syntax of XML namespaces, although there are a few caveats:

Versions 3.1.0, 3.0.3, and earlier of this specification erroneously used the term “absolute URI” instead of “non-relative URI”, so authors using namespaces that include a fragment should check tooling support carefully.
XML allows but discourages relative URI-references, while this specification outright forbids them.
XML 1.1 allows IRIs ([RFC3987]) as namespaces, and specifies that namespaces are compared without any encoding or decoding, which means that IRIs encoded to meet this specification’s URI syntax requirement cannot be compared to IRIs as-is.

Each of the following examples represent the value of the properties keyword in a Schema Object that is omitted for brevity. The JSON and YAML representations of the properties value are followed by an example XML representation produced for the single property shown.

Basic string property:

{
  "animals": {
    "type": "string"
  }
}

animals:
  type: string

<animals>...</animals>

Basic string array property (wrapped is false by default):

{
  "animals": {
    "type": "array",
    "items": {
      "type": "string"
    }
  }
}

animals:
  type: array
  items:
    type: string

<animals>...</animals>
<animals>...</animals>
<animals>...</animals>

{
  "animals": {
    "type": "string",
    "xml": {
      "name": "animal"
    }
  }
}

animals:
  type: string
  xml:
    name: animal

<animal>...</animal>

In this example, a full model definition is shown.

{
  "Person": {
    "type": "object",
    "properties": {
      "id": {
        "type": "integer",
        "format": "int32",
        "xml": {
          "attribute": true
        }
      },
      "name": {
        "type": "string",
        "xml": {
          "namespace": "https://example.com/schema/sample",
          "prefix": "sample"
        }
      }
    }
  }
}

Person:
  type: object
  properties:
    id:
      type: integer
      format: int32
      xml:
        attribute: true
    name:
      type: string
      xml:
        namespace: https://example.com/schema/sample
        prefix: sample

<Person id="123">
    <sample:name xmlns:sample="https://example.com/schema/sample">example</sample:name>
</Person>

Changing the element names:

{
  "animals": {
    "type": "array",
    "items": {
      "type": "string",
      "xml": {
        "name": "animal"
      }
    }
  }
}

animals:
  type: array
  items:
    type: string
    xml:
      name: animal

<animal>value</animal>
<animal>value</animal>

The external name field has no effect on the XML:

{
  "animals": {
    "type": "array",
    "items": {
      "type": "string",
      "xml": {
        "name": "animal"
      }
    },
    "xml": {
      "name": "aliens"
    }
  }
}

animals:
  type: array
  items:
    type: string
    xml:
      name: animal
  xml:
    name: aliens

<animal>value</animal>
<animal>value</animal>

Even when the array is wrapped, if a name is not explicitly defined, the same name will be used both internally and externally:

{
  "animals": {
    "type": "array",
    "items": {
      "type": "string"
    },
    "xml": {
      "wrapped": true
    }
  }
}

animals:
  type: array
  items:
    type: string
  xml:
    wrapped: true

<animals>
  <animals>value</animals>
  <animals>value</animals>
</animals>

To overcome the naming problem in the example above, the following definition can be used:

{
  "animals": {
    "type": "array",
    "items": {
      "type": "string",
      "xml": {
        "name": "animal"
      }
    },
    "xml": {
      "wrapped": true
    }
  }
}

animals:
  type: array
  items:
    type: string
    xml:
      name: animal
  xml:
    wrapped: true

<animals>
  <animal>value</animal>
  <animal>value</animal>
</animals>

Affecting both internal and external names:

{
  "animals": {
    "type": "array",
    "items": {
      "type": "string",
      "xml": {
        "name": "animal"
      }
    },
    "xml": {
      "name": "aliens",
      "wrapped": true
    }
  }
}

animals:
  type: array
  items:
    type: string
    xml:
      name: animal
  xml:
    name: aliens
    wrapped: true

<aliens>
  <animal>value</animal>
  <animal>value</animal>
</aliens>

If we change the external element but not the internal ones:

{
  "animals": {
    "type": "array",
    "items": {
      "type": "string"
    },
    "xml": {
      "name": "aliens",
      "wrapped": true
    }
  }
}

animals:
  type: array
  items:
    type: string
  xml:
    name: aliens
    wrapped: true

<aliens>
  <aliens>value</aliens>
  <aliens>value</aliens>
</aliens>

Defines a security scheme that can be used by the operations.

Supported schemes are HTTP authentication, an API key (either as a header, a cookie parameter or as a query parameter), mutual TLS (use of a client certificate), OAuth2’s common flows (implicit, password, client credentials and authorization code) as defined in [RFC6749], and [OpenID-Connect-Core]. Please note that as of 2020, the implicit flow is about to be deprecated by OAuth 2.0 Security Best Current Practice. Recommended for most use cases is Authorization Code Grant flow with PKCE.

Field Name	Type	Applies To	Description
type	`string`	Any	*REQUIRED*. The type of the security scheme. Valid values are `"apiKey"`, `"http"`, `"mutualTLS"`, `"oauth2"`, `"openIdConnect"`.
description	`string`	Any	A description for security scheme. [CommonMark] syntax MAY be used for rich text representation.
name	`string`	`apiKey`	*REQUIRED*. The name of the header, query or cookie parameter to be used.
in	`string`	`apiKey`	*REQUIRED*. The location of the API key. Valid values are `"query"`, `"header"`, or `"cookie"`.
scheme	`string`	`http`	*REQUIRED. The name of the HTTP Authentication scheme to be used in the Authorization header as defined in [RFC7235] Section 5.1. The values used SHOULD* be registered in the IANA Authentication Scheme registry. The value is case-insensitive, as defined in [RFC7235] Section 2.1.
bearerFormat	`string`	`http` (`"bearer"`)	A hint to the client to identify how the bearer token is formatted. Bearer tokens are usually generated by an authorization server, so this information is primarily for documentation purposes.
flows	OAuth Flows Object	`oauth2`	*REQUIRED*. An object containing configuration information for the flow types supported.
openIdConnectUrl	`string`	`openIdConnect`	*REQUIRED*. Well-known URL to discover the [OpenID-Connect-Discovery] provider metadata.

This object MAY be extended with Specification Extensions.

{
  "type": "http",
  "scheme": "basic"
}

type: http
scheme: basic

{
  "type": "apiKey",
  "name": "api-key",
  "in": "header"
}

type: apiKey
name: api-key
in: header

{
  "type": "http",
  "scheme": "bearer",
  "bearerFormat": "JWT"
}

type: http
scheme: bearer
bearerFormat: JWT

{
  "type": "mutualTLS",
  "description": "Cert must be signed by example.com CA"
}

type: mutualTLS
description: Cert must be signed by example.com CA

{
  "type": "oauth2",
  "flows": {
    "implicit": {
      "authorizationUrl": "https://example.com/api/oauth/dialog",
      "scopes": {
        "write:pets": "modify pets in your account",
        "read:pets": "read your pets"
      }
    }
  }
}

type: oauth2
flows:
  implicit:
    authorizationUrl: https://example.com/api/oauth/dialog
    scopes:
      write:pets: modify pets in your account
      read:pets: read your pets

Allows configuration of the supported OAuth Flows.

Field Name	Type	Description
implicit	OAuth Flow Object	Configuration for the OAuth Implicit flow
password	OAuth Flow Object	Configuration for the OAuth Resource Owner Password flow
clientCredentials	OAuth Flow Object	Configuration for the OAuth Client Credentials flow. Previously called `application` in OpenAPI 2.0.
authorizationCode	OAuth Flow Object	Configuration for the OAuth Authorization Code flow. Previously called `accessCode` in OpenAPI 2.0.

This object MAY be extended with Specification Extensions.

Configuration details for a supported OAuth Flow

Field Name	Type	Applies To	Description
authorizationUrl	`string`	`oauth2` (`"implicit"`, `"authorizationCode"`)	*REQUIRED. The authorization URL to be used for this flow. This MUST* be in the form of a URL. The OAuth2 standard requires the use of TLS.
tokenUrl	`string`	`oauth2` (`"password"`, `"clientCredentials"`, `"authorizationCode"`)	*REQUIRED. The token URL to be used for this flow. This MUST* be in the form of a URL. The OAuth2 standard requires the use of TLS.
refreshUrl	`string`	`oauth2`	The URL to be used for obtaining refresh tokens. This MUST be in the form of a URL. The OAuth2 standard requires the use of TLS.
scopes	Map[`string`, `string`]	`oauth2`	*REQUIRED. The available scopes for the OAuth2 security scheme. A map between the scope name and a short description for it. The map MAY* be empty.

This object MAY be extended with Specification Extensions.

{
  "type": "oauth2",
  "flows": {
    "implicit": {
      "authorizationUrl": "https://example.com/api/oauth/dialog",
      "scopes": {
        "write:pets": "modify pets in your account",
        "read:pets": "read your pets"
      }
    },
    "authorizationCode": {
      "authorizationUrl": "https://example.com/api/oauth/dialog",
      "tokenUrl": "https://example.com/api/oauth/token",
      "scopes": {
        "write:pets": "modify pets in your account",
        "read:pets": "read your pets"
      }
    }
  }
}

type: oauth2
flows:
  implicit:
    authorizationUrl: https://example.com/api/oauth/dialog
    scopes:
      write:pets: modify pets in your account
      read:pets: read your pets
  authorizationCode:
    authorizationUrl: https://example.com/api/oauth/dialog
    tokenUrl: https://example.com/api/oauth/token
    scopes:
      write:pets: modify pets in your account
      read:pets: read your pets

Lists the required security schemes to execute this operation. The name used for each property MUST correspond to a security scheme declared in the Security Schemes under the Components Object.

A Security Requirement Object MAY refer to multiple security schemes in which case all schemes MUST be satisfied for a request to be authorized. This enables support for scenarios where multiple query parameters or HTTP headers are required to convey security information.

When the security field is defined on the OpenAPI Object or Operation Object and contains multiple Security Requirement Objects, only one of the entries in the list needs to be satisfied to authorize the request. This enables support for scenarios where the API allows multiple, independent security schemes.

An empty Security Requirement Object ({}) indicates anonymous access is supported.

Field Pattern	Type	Description
{name}	[`string`]	Each name MUST correspond to a security scheme which is declared in the Security Schemes under the Components Object. If the security scheme is of type `"oauth2"` or `"openIdConnect"`, then the value is a list of scope names required for the execution, and the list MAY be empty if authorization does not require a specified scope. For other security scheme types, the array MAY contain a list of role names which are required for the execution, but are not otherwise defined or exchanged in-band.

See also Appendix F: Resolving Security Requirements in a Referenced Document for an example using Security Requirement Objects in multi-document OpenAPI Descriptions.

{
  "api_key": []
}

api_key: []

{
  "petstore_auth": ["write:pets", "read:pets"]
}

petstore_auth:
  - write:pets
  - read:pets

Optional OAuth2 security as would be defined in an OpenAPI Object or an Operation Object:

{
  "security": [
    {},
    {
      "petstore_auth": ["write:pets", "read:pets"]
    }
  ]
}

security:
  - {}
  - petstore_auth:
      - write:pets
      - read:pets

While the OpenAPI Specification tries to accommodate most use cases, additional data can be added to extend the specification at certain points.

The extensions properties are implemented as patterned fields that are always prefixed by x-.

Field Pattern	Type	Description
^x-	Any	Allows extensions to the OpenAPI Schema. The field name MUST begin with `x-`, for example, `x-internal-id`. Field names beginning `x-oai-` and `x-oas-` are reserved for uses defined by the OpenAPI Initiative. The value can be any valid JSON value (`null`, a primitive, an array, or an object.)

The OpenAPI Initiative maintains several extension registries, including registries for individual extension keywords and extension keyword namespaces.

Extensions are one of the best ways to prove the viability of proposed additions to the specification. It is therefore RECOMMENDED that implementations be designed for extensibility to support community experimentation.

Support for any one extension is OPTIONAL, and support for one extension does not imply support for others.

Some objects in the OpenAPI Specification MAY be declared and remain empty, or be completely removed, even though they are inherently the core of the API documentation.

The reasoning is to allow an additional layer of access control over the documentation. While not part of the specification itself, certain libraries MAY choose to allow access to parts of the documentation based on some form of authentication/authorization.

Two examples of this:

The Paths Object MAY be present but empty. It may be counterintuitive, but this may tell the viewer that they got to the right place, but can’t access any documentation. They would still have access to at least the Info Object which may contain additional information regarding authentication.
The Path Item Object MAY be empty. In this case, the viewer will be aware that the path exists, but will not be able to see any of its operations or parameters. This is different from hiding the path itself from the Paths Object, because the user will be aware of its existence. This allows the documentation provider to finely control what the viewer can see.

Version	Date	Notes
3.1.1	2024-10-24	Patch release of the OpenAPI Specification 3.1.1
3.1.0	2021-02-15	Release of the OpenAPI Specification 3.1.0
3.1.0-rc1	2020-10-08	rc1 of the 3.1 specification
3.1.0-rc0	2020-06-18	rc0 of the 3.1 specification
3.0.4	2024-10-24	Patch release of the OpenAPI Specification 3.0.4
3.0.3	2020-02-20	Patch release of the OpenAPI Specification 3.0.3
3.0.2	2018-10-08	Patch release of the OpenAPI Specification 3.0.2
3.0.1	2017-12-06	Patch release of the OpenAPI Specification 3.0.1
3.0.0	2017-07-26	Release of the OpenAPI Specification 3.0.0
3.0.0-rc2	2017-06-16	rc2 of the 3.0 specification
3.0.0-rc1	2017-04-27	rc1 of the 3.0 specification
3.0.0-rc0	2017-02-28	Implementer’s Draft of the 3.0 specification
2.0	2015-12-31	Donation of Swagger 2.0 to the OpenAPI Initiative
2.0	2014-09-08	Release of Swagger 2.0
1.2	2014-03-14	Initial release of the formal document.
1.1	2012-08-22	Release of Swagger 1.1
1.0	2011-08-10	First release of the Swagger Specification

Specification	Date	OAS Usage	Percent-Encoding	Notes
[RFC3986]	01/2005	URI/URL syntax	[RFC3986]	obsoletes [RFC1738], [RFC2396]
[RFC6570]	03/2012	style-based serialization	[RFC3986]	does not use `+` for `form‑urlencoded`
[RFC1866] Section 8.2.1	11/1995	content-based serialization	[RFC1738]	obsoleted by [HTML401] Section 17.13.4.1, [URL] Section 5

Object	Condition
Parameter Object	When `schema` is present
Header Object	When `schema` is present
Encoding Object	When encoding for `application/x-www-form-urlencoded` and any of `style`, `explode`, or `allowReserved` are used

field	value	equivalent
style	`"simple"`	n/a
style	`"matrix"`	`;` prefix operator
style	`"label"`	`.` prefix operator
style	`"form"`	`?` prefix operator
allowReserved	`false`	n/a
allowReserved	`true`	`+` prefix operator
explode	`false`	n/a
explode	`true`	`*` modifier suffix

OpenAPI Specification v3.1.1

Version 3.1.1

What is the OpenAPI Specification?

Status of This Document

1. OpenAPI Specification

1.1 Version 3.1.1

2. Introduction

3. Definitions

3.1 OpenAPI Description

3.2 OpenAPI Document

3.3 Schema

3.4 Object

3.5 Path Templating

3.6 Media Types

3.7 HTTP Status Codes

3.8 Case Sensitivity

3.9 Undefined and Implementation-Defined Behavior

4. Specification

4.1 Versions

4.2 Format

4.3 OpenAPI Description Structure

4.3.1 Parsing Documents

4.3.2 Structural Interoperability

4.3.3 Resolving Implicit Connections

4.4 Data Types

4.4.1 Data Type Format

4.4.2 Working with Binary Data

4.4.2.1 Migrating binary descriptions from OAS 3.0

4.5 Rich Text Formatting

4.6 Relative References in API Description URIs

4.7 Relative References in API URLs

4.8 Schema

4.8.1 OpenAPI Object

4.8.1.1 Fixed Fields

4.8.2 Info Object

4.8.2.1 Fixed Fields

4.8.2.2 Info Object Example

4.8.3 Contact Object

4.8.3.1 Fixed Fields

4.8.3.2 Contact Object Example

4.8.4 License Object

4.8.4.1 Fixed Fields

4.8.4.2 License Object Example

4.8.5 Server Object

4.8.5.1 Fixed Fields

4.8.5.2 Server Object Example

4.8.6 Server Variable Object

4.8.6.1 Fixed Fields

4.8.7 Components Object

4.8.7.1 Fixed Fields

4.8.7.2 Components Object Example

4.8.8 Paths Object

4.8.8.1 Patterned Fields

4.8.8.2 Path Templating Matching

4.8.8.3 Paths Object Example

4.8.9 Path Item Object

4.8.9.1 Fixed Fields

4.8.9.2 Path Item Object Example

4.8.10 Operation Object

4.8.10.1 Fixed Fields

4.8.10.2 Operation Object Example

4.8.11 External Documentation Object

4.8.11.1 Fixed Fields

4.8.11.2 External Documentation Object Example

4.8.12 Parameter Object

4.8.12.1 Parameter Locations

4.8.12.2 Fixed Fields

4.8.12.2.1 Common Fixed Fields

4.8.12.2.2 Fixed Fields for use with schema

4.8.12.2.3 Fixed Fields for use with content

4.8.12.3 Style Values

4.8.12.4 Style Examples

4.8.12.5 Parameter Object Examples

4.8.13 Request Body Object

4.8.13.1 Fixed Fields

4.8.13.2 Request Body Examples

4.8.14 Media Type Object

4.8.14.1 Fixed Fields

4.8.14.2 Media Type Examples

4.8.14.3 Considerations for File Uploads

4.8.12.2.2 Fixed Fields for use with `schema`

4.8.12.2.3 Fixed Fields for use with `content`

4.8.14.5 Special Considerations for `multipart` Content

4.8.15.2 Encoding the `x-www-form-urlencoded` Media Type

4.8.15.3 Encoding `multipart` Media Types

4.8.20.3 `operationRef` Examples

4.8.21.1.2 Fixed Fields for use with `schema`

4.8.21.1.3 Fixed Fields for use with `content`

4.8.24.3.2 Validating `readOnly` and `writeOnly`