API Design & Development Best Practices: Building APIs That Scale

Resource-Oriented Design

Think about your API in terms of resources (users, products, orders) not actions (getUser, createProduct). Resources are nouns, not verbs. This makes APIs intuitive and predictable.

Instead of: /getUser/123 or /createOrder
Use: GET /users/123 or POST /orders

• Use nouns for resource names: /users, /products, /orders
• Use HTTP verbs for actions: GET, POST, PUT, DELETE
• Support collections and individual resources
• Avoid nesting beyond 2 levels (keep URLs simple)

Status Codes & Error Handling

HTTP status codes communicate the outcome of a request. Use them correctly. A 200 response with an error message is confusing. A 500 error for invalid input is wrong. Use the right status code for the right situation.

• 200 OK: Request succeeded
• 201 Created: Resource created successfully
• 400 Bad Request: Invalid input from client
• 401 Unauthorized: Authentication required
• 403 Forbidden: Authenticated but unauthorized
• 404 Not Found: Resource doesn't exist
• 429 Too Many Requests: Rate limited
• 500 Internal Server Error: Server-side failure

Request/Response Format

JSON is the standard for modern APIs. Be consistent in your request and response formats. Always include metadata like pagination info, timestamps, and error details.

• Use JSON for request/response bodies
• Include metadata (pagination, timestamps, IDs)
• Provide meaningful error messages
• Use consistent naming conventions (camelCase, snake_case)

Pagination & Filtering

Large datasets need pagination. Poorly implemented pagination creates N+1 query problems and frustrates API consumers. Support filtering to help clients get exactly what they need.

• Implement cursor-based pagination for large datasets
• Support filtering on common fields
• Include total count and hasMore indicators
• Support sorting on common fields