Apache is a free and open-source cross-platform web server software.
cdnjs is a free distributed JS library delivery service.
PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.
RequireJS is a JavaScript library and file loader which manages the dependencies between JavaScript files and in modular programming.
Varnish is a reverse caching proxy.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.