ClustrMaps widget is a visitor tracker, designed for general web and blog use.
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.
Mailchimp is a marketing automation platform and email marketing service.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.