Backend API Skill

Build robust, well-documented APIs with clear contracts, proper error handling, and scalable architecture.

When to Use

Use this skill when the user wants to:

• Design or implement RESTful API endpoints
• Create GraphQL schemas and resolvers
• Handle authentication and authorization
• Work with database models and migrations
• Implement CRUD operations and data validation
• Create API documentation (OpenAPI/Swagger)

API Design Principles

• Clear contract: Define request/response formats explicitly
• Consistent naming: Use RESTful conventions (GET, POST, PUT, DELETE) or GraphQL query structure
• Versioning: Include API version in path (e.g., /api/v1/…)
• Error handling: Return meaningful error codes and messages
• Documentation: Include examples and describe fields

Code Structure

If using a framework (Express, NestJS, Fastify, etc.):

backend-api/
├── controllers/      # Request handlers
├── services/         # Business logic
├── models/           # Data models
├── routes/           # Route definitions
└── utils/            # Helper functions

Deliverables

• Complete API implementation
• Request/response examples
• Error handling strategy
• Validation schema
• API documentation (if applicable)

Quality Checklist

• Clear endpoint definitions
• Proper HTTP status codes
• Input validation
• Error responses are descriptive
• Code is documented