API routes are the solution to building your API with Next.js.

How does this work?

Files dat are inside the folder pages/api is mapped to /api/*, where it will be treated as the API endpoint instead of as a page. They will not increase client-side bundle size since they are server-side only bundles.

If you want your API route to work, you have to export a function as default, which is basically the request handler, and this will receive two parameters:

1. req is an instance of http.IncomingMessage.

   • It will also receive a few pre-built middlewares.

2. res is an instance of http.ServerResponse.

   • This will also receive a few helper functions.

If you want to handle different HTTP methods in your API route, you can use req.method in your request handler.

A good and simple example

export default function handler(req, res) {
  if (req.method === 'POST') {
    // process a POST request
  } else {
    // handle any other HTTP method
  }
}