Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
Handlebars is a JavaScript library used to create reusable webpage templates.
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.
PHP is a general-purpose scripting language used for web development.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
Select2 is a jQuery based replacement for select boxes. It supports searching, remote data sets, and infinite scrolling of results.