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Configurable module loader enabling dynamic ES module workflows in browsers and NodeJS.

SystemJS 0.20 release notes

SystemJS is currently sponsored by Canopy Tax.

Built with the ES Module Loader project, which is based on principles and APIs from the WhatWG Loader specification, modules in HTML and NodeJS.

Supports IE9+ provided a promises polyfill is available in the environment.

For discussion, join the Gitter Room.


Basic Use

Browser Development

<script src="systemjs/dist/system.js"></script>

The above will support loading all module formats.

To load ES6 code with in-browser transpilation, one of the following transpiler plugins must be configured:

Browser Production

When all modules are already transpiled into the System.register module format (which can be output via Babel or TypeScript through any build workflow), a production-only loader can be used:

<script src="systemjs/dist/system-production.js"></script>

Configuration support in the production loader includes baseURL, paths, map, contextual map, bundles and depCache.


To load modules in NodeJS, install SystemJS with:

  npm install systemjs

If transpiling ES modules, install the transpiler plugin following the instructions from the transpiler project page.

We can then load modules equivalently in NodeJS as we do in the browser:

var SystemJS = require('systemjs');
// loads './app.js' from the current directory
SystemJS.import('./app.js').then(function (m) {

To import a module with the NodeJS module resolution, import with import moduleName from '@node/module-name'.

Running the tests

  npm run build && npm run test