OpenAPI

ELI5 — The Vibe Check

OpenAPI is a standard way to describe your REST API in a YAML or JSON file. Once you have the spec, tools can auto-generate documentation, client libraries, mock servers, and tests. FastAPI generates it automatically. It's like a blueprint for your API that machines can read.

Real Talk

OpenAPI (formerly Swagger) is a specification for describing RESTful APIs in a machine-readable format (YAML/JSON). It defines endpoints, request/response schemas, authentication, and error codes. The specification enables automated documentation generation, client SDK generation, server stub generation, and API testing tools.

Show Me The Code

openapi: 3.0.0
paths:
  /users:
    get:
      summary: List users
      responses:
        '200':
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/User'

When You'll Hear This

"FastAPI generates the OpenAPI spec automatically from your type hints." / "We use the OpenAPI spec to auto-generate our TypeScript client."