cdnjs is a free distributed JS library delivery service.
Google Analytics is a free web analytics service that tracks and reports website traffic.
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.
Query Migrate is a javascript library that allows you to preserve the compatibility of your jQuery code developed for versions of jQuery older than 1.9.
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.
Linkedin Ads is a paid marketing tool that offers access to Linkedin social networks through various sponsored posts and other methods.
Modernizr is a JavaScript library that detects the features available in a user's browser.
MODX (originally MODx) is an open source content management system and web application framework for publishing content on the World Wide Web and intranets.
PHP is a general-purpose scripting language used for web development.
A modest JavaScript framework for the HTML you already have.