OpenAPI Specification (formerly Swagger) describes REST APIs in YAML/JSON. Enables: interactive docs (Swagger UI, Redoc), client/server code generation, request validation, and contract testing. Design-first approach: write the spec before code. Tools: Swagger Editor, Spectral (linting), openapi-generator.
The 5-Mode Loop
5 of 5 modes available
Read · See · Animate · Test · Build
Before this, understand: rest principles