routing-middleware

Vercel middleware intercepts requests before cache and page rendering by configuring rewrites, redirects, and header injection in a middleware.ts file or vercel.json. This allows you to route traffic and apply request rules at the platform level.

Yes, Vercel routing middleware supports A/B testing and geo-personalization in Next.js by evaluating request signals like geolocation and headers. It injects custom headers and splits traffic between variants without changing application code.

Vercel middleware supports Edge, Node.js, and Bun runtimes. You can configure request interception with matcher-based scoping and helper methods across these runtimes using middleware.ts or vercel.json.

The best way to apply header-based redirects and rewrites in Next.js is platform-level routing middleware. It evaluates request headers and URLs to send users to different paths or destinations before cache and page rendering occur.

You scope middleware execution to specific routes using matcher-based scoping configurations. This ensures your rewrites, redirects, and lightweight auth checks only intercept targeted request paths at the routing layer.