OpenAPI Specification

The OpenAPI Specification (OAS, formerly Swagger) is a standard format for describing REST APIs in a machine-readable document. An OpenAPI spec defines all available endpoints, request parameters, response schemas, authentication methods, and error codes.

Tools can automatically generate interactive documentation, client SDKs in multiple languages, server stubs, and automated tests from an OpenAPI spec - making the spec a single source of truth for everything developers need to integrate.

For developers evaluating APIs, an available OpenAPI spec is a strong signal of quality. It means the API contract is formally documented, the provider is serious about developer experience, and tooling support is available out of the box.