This guide covers the basics of implementing an API for React Storefront.


Your React Storefront app is a single page PWA that fetches data for each page from a RESTful JSON API. You can either implement your own API using Next.js API endpoints in pages/api or connect directly to a headless ecommerce API.

Example Routes

The starter app comes with example endpoints for home, subcategory, and product pages located in:

      [productId].js        // Product
      [subcategoryId].js    // Subcategory
    index.js                // Home Page

These endpoints generate mock data procedurally. You will replace them with real data when implementing your app.

App Data and Page Data

API endpoints can be called during server side rendering (when the user initially arrives at your app) or when navigating between pages. When rendering on the server, the API must return data for the page being displayed (we refer to this as "page data") as well as data required by other shared components such as the main menu, navigation, and footer (we refer to this as "app data"). For all navigation that occurs after the initial page load, only page data needs to be returned as the content of shared app components usually doesn't change. Omitting app data during subsequent minimizes response sizes and eliminates unnecessary work on the server. React Storefront provides a function to make this easy:


The fulfillAPIRequest function takes the request an an object with addData and pageData callbacks. The appData callback is only called during server side rendering. It should return a Promise that resolves to the data for shared app components such as the main menu, nav, and footer. The pageData callback is called for all requests.

import fulfillAPIRequest from 'react-storefront/props/fulfillAPIRequest'

fulfillAPIRequest(req, {
  appData: () => fetchAppData(),
  pageData: () => fetchPageData()

Implementing the API

To learn how to implement APIs for the different parts of your app, see the "Pages and Features" section of the guides.

Fetching data from the API in the browser

React Storefront appends ?__v__={__NEXT_DATA__.buildId} to all requests made from the browser using window.fetch and XMLHttpRequest. This ensures that cached results requested by a previous version of the application are not served to the current version of the application and thus prevents errors when you introduce breaking changes in your API.