Rollup
A module bundler for JavaScript
...It uses the new standardized format for code modules included in the ES6 revision of JavaScript, instead of previous idiosyncratic solutions such as CommonJS and AMD. ES modules let you freely and seamlessly combine the most useful individual functions from your favorite libraries. This will eventually be possible natively everywhere, but Rollup lets you do it today. Rollup can be used either through a command line interface with an optional configuration file, or else through its JavaScript API. Rollup allows you to write your code using the new module system, and will then compile it back down to existing supported formats such as CommonJS modules, AMD modules, and IIFE-style scripts. ...