Bootstrap is a free and open-source CSS framework directed at responsive, mobile-first front-end web development. It contains CSS and JavaScript-based design templates for typography, forms, buttons, navigation, and other interface components.
Contao is an open source CMS that allows you to create websites and scalable web applications.
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.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.
Javascript forms validation script.
PHP is a general-purpose scripting language used for web development.