OpenAPI Specification
The World Standard for RESTful APIs
The OpenAPI Specification was donated to the Linux Foundation under the OpenAPI Initiative in 2015. The specification creates a RESTful interface for easily developing and consuming an API by effectively mapping all the resources and operations associated with it.
Version 2.0: swagger 2.0
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.
https://swagger.io/specification/v2/
Version 3.0: openapi 3.0
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 RFC2119 RFC8174 when, and only when, they appear in all capitals, as shown here.
https://swagger.io/specification/