cdnjs is a free distributed JS library delivery service.
D3.js is a JavaScript library for producing dynamic, interactive data visualisations in web browsers.
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.
Open Journal Systems (OJS) is an open-source software application for managing and publishing scholarly journals.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.