Redirect and rewrite in middleware in NextJS - Step-by-Step Execution

Concept Flow - Redirect and rewrite in middleware

Request comes in

↓

Middleware runs

↓

Redirect

↓

New URL

↓

Browser

When a request arrives, middleware checks it. It can redirect the browser to a new URL or rewrite the request to serve different content without changing the URL.

Execution Sample

NextJS

import { NextResponse } from 'next/server';

export function middleware(request) {
  if (request.nextUrl.pathname === '/old') {
    return NextResponse.redirect(new URL('/new', request.url));
  }
  if (request.nextUrl.pathname === '/rewrite') {
    return NextResponse.rewrite(new URL('/api/data', request.url));
  }
}

Middleware redirects '/old' to '/new' and rewrites '/rewrite' to serve '/api/data' content.

Execution Table

Step	Request Path	Condition Checked	Action Taken	Resulting URL	Browser URL
1	/old	Is path '/old'?	Yes - Redirect	/new	/new
2	/new	Is path '/old'?	No	No action	/new
3	/rewrite	Is path '/old'?	No	Check next condition	/rewrite
4	/rewrite	Is path '/rewrite'?	Yes - Rewrite	/api/data	/rewrite

💡 Middleware stops after redirect or rewrite action; browser URL changes only on redirect.

Variable Tracker

Variable	Start	After Step 1	After Step 3	After Step 4	Final
request.nextUrl.pathname	/old	/old	/rewrite	/rewrite	/rewrite
action	none	redirect to /new	none	rewrite to /api/data	rewrite to /api/data
browser URL	/old	/new	/rewrite	/rewrite	/rewrite

Key Moments - 2 Insights

Why does the browser URL change after a redirect but not after a rewrite?

Redirect sends a response telling the browser to load a new URL, so the browser URL updates (see execution_table step 1). Rewrite changes the server's internal request path without telling the browser, so the browser URL stays the same (see step 4).

What happens if multiple conditions match in middleware?

Middleware returns immediately after the first redirect or rewrite. Later conditions are not checked (see execution_table steps 1 and 4).

Visual Quiz - 3 Questions

Look at the execution table, what is the browser URL after step 1?

A /rewrite

B /old

C /new

D /api/data

💡 Hint

Check the 'Browser URL' column in execution_table row for step 1.

At which step does the middleware perform a rewrite?

A Step 4

B Step 3

C Step 1

D Step 5

💡 Hint

Look at the 'Action Taken' column for rewrite action in execution_table.

If the request path was '/old' and the redirect was removed, what would happen at step 1?

A Redirect to /new

B No action, continue processing

C Rewrite to /api/data

D Error thrown

💡 Hint

Refer to execution_table step 1 and the conditions checked.

Concept Snapshot

Middleware intercepts requests in Next.js.
Use NextResponse.redirect() to send browser to a new URL.
Use NextResponse.rewrite() to serve different content without changing browser URL.
Redirect changes browser URL; rewrite does not.
Middleware stops after first redirect or rewrite.
Useful for URL changes and content routing.

Full Transcript

In Next.js middleware, when a request arrives, the middleware function runs first. It checks the request path. If the path is '/old', it redirects the browser to '/new', changing the browser's URL. If the path is '/rewrite', it rewrites the request internally to '/api/data' without changing the browser URL. The middleware returns immediately after redirect or rewrite, so only one action happens per request. Redirect tells the browser to load a new page, while rewrite serves different content behind the scenes. This helps manage URLs and content dynamically before the page loads.