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.
Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
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.
Plone is a free and open source content management system (CMS) built on top of the Zope application server.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.