API Design & Best Practices
Design RESTful APIs that scale. Error handling, versioning, authentication, rate limiting, and documentation.
APIs Are Contracts
An API is a contract between your backend and your frontend (or third-party developers). Break that contract, and everything breaks.
Good API design means fewer bugs, easier maintenance, and happier developers using your API.
REST Principles
Resource-Based URLs
Resources (not actions) should be the focus of your URLs.
- ✓ POST /api/projects (create)
- ✓ GET /api/projects/:id (read)
- ✓ PUT /api/projects/:id (update)
- ✗ POST /api/createProject (bad)
HTTP Methods
Use GET for fetching, POST for creating, PUT/PATCH for updating, DELETE for deleting.
Status Codes Matter
Success Responses
- 200 OK: Request succeeded
- 201 Created: Resource created
- 204 No Content: Success but no response body
Error Responses
- 400 Bad Request: Invalid input
- 401 Unauthorized: Auth required
- 403 Forbidden: Authorized but denied
- 404 Not Found: Resource doesn't exist
- 500 Internal Server Error: Server bug
Error Handling
Return Consistent Error Format
Always return structured errors with a message, error code, and details.
Never Expose Internal Details
Don't return database errors. Return user-friendly messages. Log errors server-side for debugging.
Authentication & Authorization
Use Bearer Tokens (JWT)
Include auth token in Authorization header. Validate on every protected endpoint.
Scope-Based Permissions
Users have scopes (read, write, delete). Only allow operations within their scope.
Rate Limiting
Protect Your API
Implement rate limiting to prevent abuse. Different limits for different endpoints.
Return Rate Limit Info
Include X-RateLimit-Remaining and X-RateLimit-Reset headers in responses.
Versioning Strategy
Version in URL
/api/v1/projects, /api/v2/projects. Makes versioning explicit.
Deprecation Strategy
Support old versions for at least 6 months. Notify users when a version is ending.
Documentation
Make It Clear
Use OpenAPI/Swagger. Document every endpoint, parameters, and response format.
Provide Examples
Show curl examples. Show JSON request and response bodies. Include error examples.
Design Your First API
Start with resources. Map out your endpoints. Define error responses. Write documentation. Then implement.
Key Takeaways
- •Practical tools and techniques you can implement today
- •Real-world examples from production systems
- •Common mistakes to avoid and how to fix them
Related Guides
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