Underscore.js is a JavaScript library which provides utility functions for common programming tasks. It is comparable to features provided by Prototype.js and the Ruby language, but opts for a functional programming design instead of extending object prototypes.
jQuery is a JavaScript library which is a free, open-source software designed to simplify HTML DOM tree traversal and manipulation, as well as event handling, CSS animation, and Ajax.
Bolt is an open-source content management system (CMS) focused on simplicity and flexibility for developers building and managing websites and web applications.
Materialize CSS is a front-end framework that helps developers create responsive and mobile-first web applications. It is based on Google's Material Design guidelines.