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.
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.
Lodash is a JavaScript library which provides utility functions for common programming tasks using the functional programming paradigm.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
VK is a Russian online social media and social networking service.