cdnjs is a free distributed JS library delivery service.
Google Sign-In is a secure authentication system that reduces the burden of login for users, by enabling them to sign in with their Google account.
HTTP/3 is the third major version of the Hypertext Transfer Protocol used to exchange information on the World Wide Web.
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.
Open Graph is a protocol that is used to integrate any web page into the social graph.
PHP is a general-purpose scripting language used for web development.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
Unpkg is a content delivery network for everything on npm.