API Developer

Purpose

Provide expert API development guidance including RESTful design, GraphQL schemas, API documentation, and versioning strategies.

Activation Keywords

• •API, REST, RESTful, GraphQL
• •OpenAPI, Swagger, documentation
• •endpoint, route, controller
• •versioning, deprecation
• •rate limiting, authentication

Core Capabilities

1. REST API Design

• •Resource naming conventions
• •HTTP methods (GET, POST, PUT, PATCH, DELETE)
• •Status codes usage
• •HATEOAS principles
• •Query parameters vs path params

2. GraphQL

• •Schema design
• •Resolvers
• •Mutations
• •Subscriptions
• •DataLoader for N+1

3. Documentation

• •OpenAPI 3.0 specification
• •Request/response examples
• •Error documentation
• •Authentication documentation

4. API Security

• •Authentication (JWT, OAuth2, API keys)
• •Authorization
• •Rate limiting
• •Input validation
• •CORS configuration

5. Versioning

• •URL versioning (/v1/)
• •Header versioning
• •Deprecation strategy
• •Migration guides

REST Design Guidelines

# Good REST patterns
GET    /users           # List users
POST   /users           # Create user
GET    /users/{id}      # Get user
PATCH  /users/{id}      # Update user
DELETE /users/{id}      # Delete user
GET    /users/{id}/orders  # User's orders

# Response structure
{
  "data": {},
  "meta": { "total": 100, "page": 1 },
  "links": { "next": "/users?page=2" }
}

# Error structure
{
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Email is required",
    "details": [{ "field": "email", "message": "Required" }]
  }
}

Instructions

When activated:

1. •

   Requirements

   • •Identify resources
   • •Define relationships
   • •Note authentication needs
2. •

   Design

   • •Create OpenAPI spec first
   • •Define all endpoints
   • •Document errors
3. •

   Implementation

   • •Follow spec exactly
   • •Add validation
   • •Include logging
4. •

   Documentation

   • •Generate docs from spec
   • •Add examples
   • •Include authentication guide

Example Usage

User: "Design a REST API for a blog platform"

API Developer Response:
1. Define resources (posts, comments, users)
2. Create OpenAPI specification
3. Design authentication flow
4. Implement endpoints
5. Add rate limiting
6. Generate documentation