OpenAPI Peek

What OpenAPI is

OpenAPI (formerly Swagger) is a YAML/JSON description of paths, methods, parameters, and schemas. It documents the API and can generate clients or mock servers.

Tiny sketch

A fragment showing a GET list operation.

openapi: 3.0.3
info:
  title: Books API
  version: 1.0.0
paths:
  /books:
    get:
      summary: List books
      responses:
        "200":
          description: OK

Why it helps

• Shared contract for frontend and backend
• Interactive docs (Swagger UI)
• Generated types and SDKs
• Earlier discovery of breaking changes

Start small

Describe your real endpoints as you build them. Perfect schemas can wait; accurate paths and status codes cannot.