REST API Design: Best Practices and Common Mistakes

A well-designed API is a joy to use. A poorly designed one causes frustration and bugs. Here's how to design APIs that developers love.

Core Principles

1. Use Nouns, Not Verbs

✅ GET /users
❌ GET /getUsers

2. Use HTTP Methods Correctly

• GET: Read data
• POST: Create data
• PUT: Update (replace) data
• PATCH: Partial update
• DELETE: Remove data

3. Use Proper Status Codes

• 200: Success
• 201: Created
• 400: Bad Request
• 401: Unauthorized
• 404: Not Found
• 500: Server Error

Response Format

Consistent Structure

Always return data in a consistent format with proper error objects including code, message, and details.

Pagination

For list endpoints, include pagination metadata with total items, page number, items per page, and total pages.

Versioning

URL Versioning

Most common and explicit: /api/v1/users

Header Versioning

Cleaner URLs but less visible: Accept: application/vnd.api+json;version=1

Authentication

JWT (JSON Web Tokens)

Stateless, scalable, good for SPAs and mobile apps.

API Keys

Simple, good for server-to-server communication.

OAuth 2.0

For third-party access and complex authorization.

Documentation

OpenAPI/Swagger

Standard for API documentation with interactive testing.

Examples

Always include request/response examples.

Common Mistakes

1. Not using HTTPS: Always encrypt in production
2. Exposing sensitive data: Be careful what you return
3. No rate limiting: Protect against abuse
4. Poor error messages: Help developers debug

Conclusion

Good API design takes time but pays dividends in developer experience and reduced support burden.