OpenAPI 3.0 is an open specification for defining REST APIs.
The OpenAPI 3.0 Specification (OAS) defines a standard, language-agnostic interface to RESTful APIs, which allows both humans and computers to discover and understand the capabilities of the service without access to source code, documentation, or through network traffic inspection. When properly defined, a consumer can understand and interact with the remote service with a minimal amount of implementation logic.
An OpenAPI 3.0 definition can then be used by documentation generation tools to display the API, code generation tools to generate servers and clients in various programming languages, testing tools, and many other use cases.
IBM® App Connect Enterprise supports version 3.0 of the OpenAPI specification with some restrictions. For more information, see https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.0.md and Restrictions on OpenAPI 3.0 documents.