Bootstrap is a free and open-source CSS framework directed at responsive, mobile-first front-end web development. It contains CSS and JavaScript-based design templates for typography, forms, buttons, navigation, and other interface components.
cdnjs is a free distributed JS library delivery service.
Java is a class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible.
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.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
SweetAlert2 is a JavaScript library that provides customisable, visually appealing, and responsive alert and modal dialog boxes for web applications.
Unpkg is a content delivery network for everything on npm.