The OpenAPI Guide: Spec, 3.2, Design, and How It Works

Quick answer: OpenAPI is a machine-readable contract that describes an HTTP API — its paths, operations, request and response shapes, authentication, and examples. Treat it as the single source of truth and let it drive design, debugging, testing, mocking, documentation, code generation, and MCP servers. The spec pays off when it lives in version control, gets validated in CI, and is written…