Route Handlers and Middleware

Route Handlers

Route Handlers allow you to create custom request handlers for a given route using the Web Requestand ResponseAPIs.

Good to know: Route Handlers are only available inside the app directory. They are the equivalent of API Routes inside the pages directory meaning you do not need to use API Routes and Route Handlers together.

Convention

Route Handlers are defined in a route.js|ts file inside the app directory:

export async function GET(request: Request) {}

Route Handlers can be nested anywhere inside the app directory, similar to page.js and layout.js. But there cannot be a route.js file at the same route segment level as page.js.

Supported HTTP Methods

The following HTTP methodsare supported: GET, POST, PUT, , DELETE, HEAD, and OPTIONS. If an unsupported method is called, Next.js will return a 405 Method Not Allowed response.

Extended NextRequest and NextResponse APIs

In addition to supporting the native Requestand ResponseAPIs, Next.js extends them with NextRequest and NextResponse to provide convenient helpers for advanced use cases.

Caching

Route Handlers are not cached by default. You can, however, opt into caching for GET methods. Other supported HTTP methods are not cached. To cache a GET method, use a route config option such as export const dynamic = 'force-static' in your Route Handler file.

export const dynamic = 'force-static'
 
export async function GET() {
  const res = await fetch('https://data.mongodb-api.com/...', {
    headers: {
      'Content-Type': 'application/json',
      'API-Key': process.env.DATA_API_KEY,
    },
  })
  const data = await res.json()
 
  return Response.json({ data })
}

Good to know: Other supported HTTP methods are not cached, even if they are placed alongside a GET method that is cached, in the same file.

Special Route Handlers

Special Route Handlers like sitemap.ts, opengraph-image.tsx, and icon.tsx, and other metadata files remain static by default unless they use Dynamic APIs or dynamic config options.

Route Resolution

You can consider a route the lowest level routing primitive.

• They do not participate in layouts or client-side navigations like page.
• There cannot be a route.js file at the same route as page.js.

Each route.js or page.js file takes over all HTTP verbs for that route.

export default function Page() {
  return <h1>Hello, Next.js!</h1>
}
 
// ❌ Conflict
// `app/route.ts`
export async function POST(request: Request) {}

Read more about how Route Handlers complement your frontend application, or explore the Route Handlers API Reference.

Middleware

Middleware allows you to run code before a request is completed. Then, based on the incoming request, you can modify the response by rewriting, redirecting, modifying the request or response headers, or responding directly.

Use cases

Some common scenarios where Middleware is effective include:

• Quick redirects after reading parts of the incoming request
• Rewriting to different pages based on A/B tests or experiments
• Modifying headers for all pages or a subset of pages

Middleware is not a good fit for:

• Slow data fetching
• Session management

Using fetch with options.cache, options.next.revalidate, or options.next.tags, has no effect in Middleware.

Convention

Use the file middleware.ts (or .js) in the root of your project to define Middleware. For example, at the same level as pages or app, or inside src if applicable.

Note: While only one middleware.ts file is supported per project, you can still organize your middleware logic into modules. Break out middleware functionalities into separate .ts or .js files and import them into your main middleware.ts file. This allows for cleaner management of route-specific middleware, aggregated in the middleware.ts for centralized control. By enforcing a single middleware file, it simplifies configuration, prevents potential conflicts, and optimizes performance by avoiding multiple middleware layers.

Example

import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'
 
// This function can be marked `async` if using `await` inside
export function middleware(request: NextRequest) {
  return NextResponse.redirect(new URL('/home', request.url))
}
 
// See "Matching Paths" below to learn more
export const config = {
  matcher: '/about/:path*',
}

Read more about using middleware, or refer to the middleware API reference.