How to link Gatsby.js with my Express server

Add this to your Gatsby-config file

module.exports = {
  proxy: {
    prefix: "/users",
    url: "http://localhost:3000",
  },
}

This way, when you fetch('/users/todos') in development, the development server will recognize that it’s not a static asset, and will proxy your request to http://localhost:3000/users/todos as a fallback.