Apache is a free and open-source cross-platform web server software.
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.
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.
Popper is a positioning engine, its purpose is to calculate the position of an element to make it possible to position it near a given reference element.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.