AddThis is a social bookmarking service that can be integrated into a website with the use of a web widget.
Drupal Multisite enables separate, independent sites to be served from a single codebase.
Drupal is a free and open-source web content management framework.
Headroom.js is a JS widget that allows you to react to the user's scroll. The header slides out of view when scrolling down and slides back in when scrolling up.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
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.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Optimizely is an experimentation platform that helps developers build and run A/B tests on websites.
Pantheon is a WebOps (Website Operations) and Management Platform for WordPress and Drupal.
Varnish is a reverse caching proxy.