Next.js middleware runs before requests are completed. Here's how to use it for authentication, redirects, and more.
Basic Middleware
Loading code block...
Authentication Middleware
Loading code block...
Role-Based Access Control
Loading code block...
Geolocation and Localization
Loading code block...
A/B Testing
Loading code block...
Rate Limiting
Loading code block...
Request/Response Modification
Loading code block...
Combining Multiple Middleware
Loading code block...
Best Practices
Performance:
✓ Keep middleware fast (runs on every request)
✓ Avoid heavy computations
✓ Use Edge runtime efficiently
✓ Cache when possible
Security:
✓ Validate tokens properly
✓ Sanitize inputs
✓ Set security headers
✓ Handle errors gracefully
Configuration:
✓ Use specific matchers
✓ Exclude static files
✓ Order middleware logically
✓ Test all paths
Conclusion
Next.js middleware enables powerful request-time logic including authentication, localization, A/B testing, and rate limiting. Keep middleware fast since it runs on every matched request. Use specific matchers to avoid unnecessary execution and combine multiple concerns thoughtfully.