Next.js middleware runs before requests are completed. Here's how to use it for authentication, redirects, and more.
Basic Middleware#
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Authentication Middleware#
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Role-Based Access Control#
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Geolocation and Localization#
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A/B Testing#
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Rate Limiting#
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Request/Response Modification#
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Combining Multiple Middleware#
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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.