Next.js 15 Middleware: Edge Guide for Auth & Rate Limiting
Comprehensive guide to Next.js 15 middleware patterns for production apps covering authentication, rate limiting, and Edge runtime.
Stock photo for illustration only, not from the actual event
- Middleware handles auth, rate limiting, and security headers cleanly in a single file.
- Executes on the Vercel Edge Runtime for optimal speed and geolocation support.
- Compose helpers from cheapest to most expensive for optimal performance.
- Next.js 16 deprecates middleware and renames the convention to proxy.
Middleware is the most underused primitive in Next.js. Teams write one middleware for auth, ship it, and never touch it again. Meanwhile, they bolt rate limiting into API routes one by one, run A/B tests via client-side flicker, and set security headers in fifteen different places.
Middleware does all of that cleanly in one place. This guide covers every pattern production Next.js 15 apps actually need:
- Authentication
- Rate limiting
- A/B testing
- Geolocation
- Bot blocking
- CSP headers
- Structured request logging
Stock photo for illustration only, not from the actual event
Every pattern above runs in the Vercel Edge Runtime. If you deploy elsewhere, most of it still works, but some patterns like geolocation via request headers are Vercel-specific.
Running middleware at the Edge layer allows applications to intercept requests before hitting core business logic. Proper composition of helper functions ensures that latency remains low and scalable across global user bases.
In Next.js 16.0.0, the middleware file convention was deprecated and renamed to proxy. Everything in this guide still applies, and developers can use the provided codemod to automate the migration process smoothly.
Source: Dev.to
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