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 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.
Lightbox is small javascript library used to overlay images on top of the current page.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Sulu is the go-to CMS for back-end projects written within the PHP Symfony framework.