How do I auto-generate docs for a REST API?

Auto-generating REST API docs usually means two things:

1. Extracting an API spec from your code or source of truth
2. Rendering that spec into human-friendly documentation

The most common and reliable approach is to use an OpenAPI (Swagger) spec.

Typical workflow

1. Define your API in OpenAPI

Write or generate an openapi.yaml or openapi.json file describing:

• endpoints
• HTTP methods
• request bodies
• query/path parameters
• responses
• authentication
• schemas/models

Example:

openapi: 3.0.3
info:
  title: My API
  version: 1.0.0
paths:
  /users:
    get:
      summary: List users
      responses:
        '200':
          description: OK

2. Generate interactive docs

Use tools like:

• Swagger UI — interactive docs and “Try it out”
• Redoc — clean, readable documentation
• Stoplight Elements — another docs renderer

These tools read your OpenAPI file and produce docs automatically.

3. Keep docs in sync

To reduce manual work, generate the OpenAPI spec from your code/framework if possible.

Examples:

• FastAPI: auto-generates OpenAPI from type hints and docstrings
• Spring Boot: use springdoc-openapi
• Express/NestJS: use decorators or annotations
• Django REST Framework: drf-spectacular or drf-yasg
• Go: swaggo, go-swagger

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Common options by stack

FastAPI (Python)

Docs are basically free:

• /docs → Swagger UI
• /redoc → Redoc

Spring Boot (Java)

Use:

• springdoc-openapi-starter-webmvc-ui

Then visit:

• /swagger-ui.html or /swagger-ui/index.html
• /v3/api-docs

Express (Node.js)

Common choices:

• swagger-jsdoc + swagger-ui-express
• or use NestJS decorators if on Nest

Django REST Framework

Use:

• drf-spectacular
• drf-yasg

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Best practice

Use OpenAPI as the source of truth, then generate:

• docs website
• SDKs
• validation
• mock servers
• tests

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If you want “from code comments”

That’s possible, but less reliable. Tools can read:

• annotations/decorators
• docstrings
• JSDoc comments

Still, the output usually ends up as an OpenAPI spec.

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Recommended setup

If you want the simplest durable solution:

• Generate OpenAPI from code
• Render with Swagger UI or Redoc
• Serve the spec at a public endpoint
• Add CI checks to ensure docs are updated

If you tell me your framework/language, I can give you the exact setup and example code.