Calendly is an app for scheduling appointments, meetings, and events.
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.
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.
Popper is a positioning engine, its purpose is to calculate the position of an element to make it possible to position it near a given reference element.
Ruby on Rails is a server-side web application framework written in Ruby under the MIT License.
A modest JavaScript framework for the HTML you already have.
Tippy.js is the complete tooltip, popover, dropdown, and menu solution for the web, powered by Popper.
Unpkg is a content delivery network for everything on npm.