Webpacker - Use Webpack to manage app-like JavaScript modules in Rails - rails/webpacker

Grunt - The Grunt ecosystem is huge and it's growing every day.

Webpack - Webpack is a module bundler. Its main purpose is to bundle JavaScript files for usage in a browser, yet it is also capable of transforming, bundling, or packaging just about any resource or asset.

Parcel - Blazing fast, zero configuration web application bundler

Brunch - Brunch builds, lints, compiles, concatenates and shrinks your HTML5 app in an ultra-simple way. No more Grunt / Gulp mess.

rollup.js - Rollup is a module bundler for JavaScript which compiles small pieces of code into a larger piece such as application.