Apache is a free and open-source cross-platform web server software.
cdnjs is a free distributed JS library delivery service.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
RxJS is a reactive library used to implement reactive programming to deal with async implementation, callbacks, and event-based programs.
SockJS is a browser JavaScript library that provides a WebSocket-like object.
Unpkg is a content delivery network for everything on npm.