cdnjs is a free distributed JS library delivery service.
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.
Matter.js is a 2D physics engine for the web. It provides JavaScript-based tools for simulating rigid body physics in 2D environments.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Tilda is a web design tool.