routing-middleware

Intercept and route HTTP requests before the CDN cache on Vercel by using platform-level middleware. This mechanism runs before cache generation, enabling you to apply rewrites, redirects, and header injection for incoming traffic across any supported framework.

Use proxy.ts instead of middleware.ts for Next.js routing when migrating to Next.js 16. The proxy.ts file handles platform-level request interception on Edge, Node.js, and Bun runtimes, serving as the modern standard for pre-cache routing controls.

Yes, you can use Vercel middleware for geo-routing and A/B testing in SvelteKit, Astro, or Nuxt. The middleware runs at the platform level before cache, allowing you to route requests dynamically based on geolocation or Edge Config data.

Limitations of using Edge middleware include strict request size and header limits. You should avoid heavy server-side logic, delegating authentication or background processing safely to proxy skills while configuring matchers to restrict execution scope.

Configure matchers in your middleware file to target specific path patterns for project-level route updates. This restricts the middleware execution scope, allowing instant route updates and header injection without triggering a full application redeployment.

Yes, Vercel routing middleware supports header injection for proxies across Edge, Node.js, and Bun runtimes. You can safely chain the middleware to auth or proxy skills while satisfying runtime selection and request size constraints.