To proxy to backend with default Next.js dev server, we configure our Next.js config with the URL rewrite.

For instance, in next.config.js, we write

module.exports = {
  async rewrites() {
    return [
      {
        source: "/api/:path*",
        destination: "http://localhost:8000/:path*",
      },
    ];
  },
};

to return an array with an object with the source path and the destination path which we redirect the source path to.

This lets us create a proxy to the back end for our Next.js app