cdnjs is a free distributed JS library delivery service.
D3.js is a JavaScript library for producing dynamic, interactive data visualisations in web browsers.
EmailJS is a cloud-based email delivery service that allows you to send emails directly from your client-side JavaScript code without the need for a server-side implementation.
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.
Sucuri is a cybersecurity company that provides website security solutions and services.
Unpkg is a content delivery network for everything on npm.