cdnjs is a free distributed JS library delivery service.
Drupal is a free and open-source web content management framework.
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.
Leaflet is the open-source JavaScript library for mobile-friendly interactive maps.
PHP is a general-purpose scripting language used for web development.
Select2 is a jQuery based replacement for select boxes. It supports searching, remote data sets, and infinite scrolling of results.
Unpkg is a content delivery network for everything on npm.