API Documentation Generator#

Generate comprehensive API documentation by analyzing source code. Extracts endpoints, parameters, request/response schemas, authentication requirements, and generates examples. Works with Express, FastAPI, Django REST Framework, Rails, Spring Boot, and other frameworks.

Usage#

text

"Generate API docs from my Express app"
"Create API reference documentation"
"Document all endpoints in this project"
"Generate OpenAPI spec from my code"

How It Works#

1. Framework Detection#

bash

# Detect framework from dependencies
cat package.json 2>/dev/null | python3 -c "
import json,sys
d=json.load(sys.stdin).get('dependencies',{})
for fw in ['express','fastify','koa','hapi','nestjs','next']:
    if fw in str(d): print(f'Node: {fw}')
" 2>/dev/null

cat requirements.txt setup.py pyproject.toml 2>/dev/null | grep -i "fastapi\|django\|flask\|starlette"

2. Endpoint Extraction#

Scan source code for route definitions:

Express/Node:

bash

grep -rn "router\.\(get\|post\|put\|patch\|delete\|all\)\|app\.\(get\|post\|put\|patch\|delete\)" src/ routes/

FastAPI/Python:

bash

grep -rn "@app\.\(get\|post\|put\|patch\|delete\)\|@router\.\(get\|post\|put\|patch\|delete\)" src/ app/

Django REST Framework:

bash

grep -rn "class.*ViewSet\|class.*APIView\|path(" */views.py */urls.py

For each endpoint, extract:

• HTTP method and path
• URL parameters and query parameters
• Request body schema (from TypeScript types, Pydantic models, serializers)
• Response format and status codes
• Authentication requirements
• Middleware chain
• Rate limiting rules

3. Schema Extraction#

Analyze types/models for request/response schemas:

• TypeScript interfaces and types
• Pydantic models with field validators
• Django serializers with field definitions
• Joi/Zod validation schemas
• JSON Schema definitions

4. Example Generation#

Generate realistic request/response examples:

• Valid request with all required fields
• Response with realistic data
• Error response examples (400, 401, 403, 404, 500)
• Curl command for quick testing
• SDK examples in popular languages

5. Documentation Output#

Generate in multiple formats:

Markdown API Reference:

markdown

## POST /api/users

Create a new user account.

**Authentication:** Bearer token required
**Rate limit:** 10 requests/minute

### Request Body
| Field | Type | Required | Description |
|-------|------|----------|-------------|
| email | string | yes | Valid email address |
| name | string | yes | Full name (2-100 chars) |
| role | enum | no | "user" or "admin" (default: "user") |

### Response (201 Created)
```json
{
  "id": "usr_abc123",
  "email": "user@example.com",
  "name": "Jane Smith",
  "role": "user",
  "createdAt": "2026-04-30T10:00:00Z"
}

Errors#

• 400 — Invalid email format or missing required field
• 409 — Email already registered
• 429 — Rate limit exceeded

text

**OpenAPI 3.1 spec** — machine-readable for Swagger UI, Redoc, Postman

### 6. Completeness Check

Verify documentation quality:
- All endpoints documented
- All parameters described
- Response schemas match actual responses
- Authentication documented
- Error codes listed
- Examples present and valid

## Output

API Documentation Generated#

Framework: Express.js + TypeScript Endpoints found: 23 Documentation completeness: 87%

Generated Files#

• docs/api-reference.md (full markdown reference)
• docs/openapi.yaml (OpenAPI 3.1 spec)
• docs/examples/ (curl examples per endpoint)

Coverage#

CategoryEndpointsDocumentedMissingAuth44 (100%)—Users65 (83%)PATCH /users/:idOrders87 (88%)webhook handlerAdmin55 (100%)—

Undocumented#

• PATCH /api/users/:id — has route but no type annotations
• POST /api/webhooks/stripe — raw req.body, no schema

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