cdnjs is a free distributed JS library delivery service.
Disqus is a worldwide blog comment hosting service for web sites and online communities that use a networked platform.
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.
MathJax is a cross-browser JavaScript library that displays mathematical notation in web browsers, using MathML, LaTeX and ASCIIMathML markup.
Modernizr is a JavaScript library that detects the features available in a user's browser.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.