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.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
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.
Lightbox is small javascript library used to overlay images on top of the current page.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
UserWay is a web accessibility overlay for websites that claims to improve compliance with accessibility standards.