Gulp.js - Automate and enhance your workflow
RequireJS - RequireJS is a JavaScript file and module loader.
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.
npm - npm is a package manager for Node.
Gear.js - Easy to use, simple to extend, and powerful build system.