OpenAPI is the actual open, vendor-neutral specification format (a JSON/YAML schema) for describing a REST API's endpoints, parameters, request/response shapes, and authentication requirements. 'Swagger' originally referred to the specification itself before it was donated and renamed OpenAPI — today, 'Swagger' generally refers to the family of tooling built around the OpenAPI spec (Swagger UI for interactive browsing, Swagger Editor, Swagger Codegen for generating client SDKs), while OpenAPI is the name of the underlying format those tools consume and produce.

Intermediate5 min

AccentureCapgeminiCognizantOracleIBMAmazon

#OpenAPI Specification#Swagger

What is the OpenAPI specification, and how does it relate to Swagger?

The Generated Spec Enables More Than Just Documentation

Because the OpenAPI JSON is a fully machine-readable contract, it's not just useful for human-browsable docs — it can drive automated client SDK generation for other languages/services, contract testing (verifying the API still matches its documented shape), and even mock server generation for frontend teams to develop against before the real backend is finished, all from the exact same generated spec.