Middleware

Middleware runs before every request, letting you modify the request or response, redirect users, or add headers.

Basic usage

Create a middleware.ts file in your project root:

import { NextResponse } from "@limlabs/rex/middleware";
import type { NextRequest } from "@limlabs/rex/middleware";

export function middleware(request: NextRequest) {
  // Add a custom header to every response
  return NextResponse.next({
    headers: { "x-powered-by": "rex" },
  });
}

Redirects

import { NextResponse } from "@limlabs/rex/middleware";
import type { NextRequest } from "@limlabs/rex/middleware";

export function middleware(request: NextRequest) {
  if (request.nextUrl.pathname === "/old-page") {
    return NextResponse.redirect(new URL("/new-page", request.url));
  }

  return NextResponse.next();
}

Matchers

By default, middleware runs on every route. Use the config export to limit which routes it applies to:

import { NextResponse } from "@limlabs/rex/middleware";
import type { NextRequest } from "@limlabs/rex/middleware";

export const config = {
  matcher: ["/dashboard/:path*", "/api/:path*"],
};

export function middleware(request: NextRequest) {
  // Only runs for /dashboard/* and /api/* routes
  const token = request.headers["authorization"];
  if (!token) {
    return NextResponse.redirect(new URL("/login", request.url));
  }
  return NextResponse.next();
}

Execution order

Middleware runs after static file resolution but before page rendering:

1. Static file check (public/ directory)
2. Middleware executes
3. Route matching
4. Data fetching (getServerSideProps / getStaticProps)
5. Page rendering (SSR)