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.
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.
Progressive Web Apps (PWAs) are web apps built and enhanced with modern APIs to deliver enhanced capabilities, reliability, and installability while reaching anyone, anywhere, on any device, all with a single codebase.
Ruby on Rails is a server-side web application framework written in Ruby under the MIT License.
Unpkg is a content delivery network for everything on npm.