Develop a React App against a Shared Mirage Server

Once you're ready to centralize your Mirage server and share it between development and testing, follow these steps.

Step 1: Install Mirage

First, make sure you've added Mirage to your project:

# Using npm
npm install --save-dev miragejs

# Using Yarn
yarn add --dev miragejs

Step 2: Define your shared server

A common place to define your shared server is src/server.js:

// src/server.js
import { createServer, Model } from "miragejs"

export function makeServer({ environment = "test" } = {}) {
  let server = createServer({

    models: {
      user: Model,

    seeds(server) {
      server.create("user", { name: "Bob" })
      server.create("user", { name: "Alice" })

    routes() {
      this.namespace = "api"

      this.get("/users", (schema) => {
        return schema.users.all()

  return server

In an app build with Create React App, make sure this file is under the src/ directory so that changes to it trigger rebuilds.

The environment argument we're adding to the function signature is just a convention. We're defaulting it to test since in most apps, you'll call makeServer once in development mode but many times in test (across your various test files).

You are free to change the signature to whatever you like.

Step 3: Start your server in development

Open your React app's bootstrap file (src/index.js in a Create React App), import your makeServer function, and call it in the development environment:

// src/index.js
import React from "react"
import ReactDOM from "react-dom"
import App from "./App"
import { makeServer } from "./server"

if (process.env.NODE_ENV === "development") {
  makeServer({ environment: "development" })

ReactDOM.render(<App />, document.getElementById("root"))

We're using the process.env.NODE_ENV environment variable here, which is a common global variable available in many React app environments. The conditional allows Mirage to be tree-shaken in production, so it won't affect your production bundle.

Also, note that we're passing in { environment: "development" } here, so that Mirage's seeds() load and there is some simulated latency to help you during development.

And that's it! With this code in place, whenever any component in your application makes a network request in development, Mirage will intercept that request and respond with the data from your server definition.

You now have a central place to define and update your Mirage server as you continue local development on your React app.