Apache is a free and open-source cross-platform web server software.
cdnjs is a free distributed JS library delivery service.
A multi-dimensional charting library built to work natively with crossfilter and rendered using d3.js
Google Analytics is a free web analytics service that tracks and reports website traffic.
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.
JSDelivr is a free public CDN for open-source projects. It can serve web files directly from the npm registry and GitHub repositories without any configuration.
Leaflet is the open-source JavaScript library for mobile-friendly interactive maps.
MathJax is a cross-browser JavaScript library that displays mathematical notation in web browsers, using MathML, LaTeX and ASCIIMathML markup.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Progressive Web Apps (PWAs) are web apps built and enhanced with modern APIs to deliver enhanced capabilities, reliability, and installability while reaching anyone, anywhere, on any device, all with a single codebase.
Unpkg is a content delivery network for everything on npm.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.