API Documentation

Create comprehensive API documentation with clear references, code examples, and developer guides for easy integration.

When to Use This Skill

• Documenting REST APIs
• Creating API references
• Writing integration guides
• Providing code examples
• Documenting authentication
• Explaining error codes
• Rate limiting documentation
• SDK documentation

Core Concepts

1. API Reference Structure

## GET /users/{id}

Retrieve a user by ID.

### Parameters

| Name | Type | Required | Description |
|------|------|----------|-------------|
| id | string | Yes | User ID |

### Request Example

```bash
curl -X GET https://api.example.com/users/123 \
  -H "Authorization: Bearer YOUR_TOKEN"

Response Example (200 OK)

{
  "id": "123",
  "name": "John Doe",
  "email": "john@example.com",
  "created_at": "2024-01-01T00:00:00Z"
}

Error Responses

### 2. OpenAPI Specification

```yaml
openapi: 3.0.0
info:
  title: User API
  version: 1.0.0
paths:
  /users/{id}:
    get:
      summary: Get user by ID
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: string
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/User'
components:
  schemas:
    User:
      type: object
      properties:
        id:
          type: string
        name:
          type: string
        email:
          type: string

Best Practices

1. Clear examples – Show request and response
2. Complete references – All parameters documented
3. Error codes – Document all possible errors
4. Code samples – Multiple languages
5. Authentication – Clear auth instructions
6. Rate limits – Document limits and headers
7. Versioning – Version strategy documented
8. Try it out – Interactive API explorer

Resources

• OpenAPI Specification: https://swagger.io/specification/
• Postman Documentation: Generate docs from collections