Next.js Middleware

ELI5 — The Vibe Check

Next.js Middleware is like a bouncer that intercepts every request before it reaches your page. It runs at the edge (close to the user) and can redirect, rewrite, or modify requests on the fly. Need to check if someone's logged in before showing a page? Middleware's got you. Need A/B testing? Middleware winks and makes it happen.

Real Talk

Next.js Middleware executes before a request completes, running on the Edge Runtime. It can rewrite URLs, redirect users, set headers, and modify responses. It's commonly used for authentication checks, A/B testing, geolocation-based routing, and bot protection. It runs in every Vercel region for low latency.

When You'll Hear This

"Our middleware redirects unauthenticated users to the login page before the page even renders." / "We use Next.js middleware for A/B testing — users get assigned a variant at the edge."