node package manager


Server-side rendering tool for your web app. Prerenders your app into static HTML files and supports routing.

prep npm version CircleCI

Pre-renders your web app into static HTML based on your specified routes enabling SEO for single page applications.


  • ūüĒé Makes your single page app SEO friendly
  • ūüöÄ Improves loading speed up to 400x
  • ‚ú® Incredibly flexible and easy to use
  • ūüď¶ Works out-of-the-box with any framework (React, Angular, Backbone...). No code-changes needed.


npm install -g prep


Just run prep in your terminal or add it to the scripts as part of your build step in your package.json. If you don't provide a target-dir the contents of the source-dir will be overwritten.

  Usage: prep [options] <source-dir> [target-dir]
    -h, --help           output usage information
    -c, --config [path]  Config file (Default: prep.js)
    -p, --port [port]    Phantom server port (Default: 45678)

In order to configure the routes which you'd like to pre-render you need to specifiy them in a Javascript config file with the following schema. If you don't provide a config file, prep will just pre-render the / route.

const defaultConfig = {
  routes: ['/'],
  timeout: 1000,
  dimensions: {
    width: 1440,
    height: 900,
  https: false,
  hostname: 'http://localhost',
  useragent: 'Prep',
  minify: false,
  • routes specifies the list of routes that the renderer should pass. (Default: ['/'])
  • timeout is the timeout for how long the renderer should wait for network requests. (Default: 1000)
  • dimensions the page dimensions in pixels that the renderer should use to render the site. (Default: 1440 x 900)
  • https prep uses https if true otherwise http
  • hostname is used to show the correct urls in the generated sitemap that is stored in [target-dir]/sitemap.xml
  • useragent is set a navigator.userAgent
  • minify is a boolean or a html-minifier configuration object.

Example prep.js

There are three different ways to configure prep. Which one you pick depends on your use case.

1. Javascript Object

The probably easiest way is to export a simple Javascript object.

exports.default = {
  routes: [

2. Synchronous Function

You can also return a function that returns the config for prep.

exports.default = () => {
  return {
    routes: [

3. Asynchronous Function (Promise)

Furthermore you can also return a Promise or use ES7 features such as async & await (Babel pre-compile step needed).

export default async () => {
  const routes = await getRoutesAsync()
  return { routes }

How it works

The concept behind prep is very simple. prep starts a temporary local webserver and opens your provided routes via PhantomJS. Each route will be exported as a static HTML file. The resulting folder structure is the same as the structure of your routes.

Known Issues

  • If you want to use Object.assign() in your code, please add a polyfill like phantomjs-polyfill-object-assign, because prep uses PhantomJS, which doesn't support Object.assign() yet.

Help & Community Slack Status

Join our Slack community if you run into issues or have questions. We love talking to you!