cdnjs is a free distributed JS library delivery service.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
SweetAlert is a JavaScript library that provides alternative alert and modal dialog boxes for web applications, with customisable features, aiming to improve the user interface of the default browser dialogs.
Unpkg is a content delivery network for everything on npm.
Vue.js is an open-source model–view–viewmodel JavaScript framework for building user interfaces and single-page applications.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.