API routes

Learn to write route handlers in Next.js.

API routes

In Next.js App Router, API routes are defined in app/api/... as route.js files. Each file exports functions that handle HTTP requests.

For example, app/api/hello/route.js answers /api/hello. You write separate functions for GET, POST, PUT, DELETE.

API routes run on the server; no JavaScript is sent to the client.

HTTP methods

You write a separate exported function per HTTP method: export async function GET(request), export async function POST(request) and so on. Next.js runs the matching function based on the request method.

Undefined methods return 405. This is the standard REST API approach.

Functions should be async because they usually wait on a database or external API.

Exercise First API route

Write a GET function: take request as parameter, return new Response("Hello API"). The function must be async and exported.

Show example solution

// app/api/hello/route.js
export async function GET(request) {
  return new Response("Hello API");
}

Test yourself

Which file defines an API route?
- route.js
- page.js
- api.js
- server.js
Show answer

route.js — app/api/.../route.js is the API route.

GET function

export async function ____(request) {
  return new Response("Merhaba");
}

Show answer

export async function GET(request) {
  return new Response("Merhaba");
}

API routes: match the terms

route.js

API file
GET

Read
POST

Write
DELETE

Delete

Next lesson: GET and POST

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