Calendly is an app for scheduling appointments, meetings, and events.
Express is a web application framework for Node.js, released as free and open-source software under the MIT License. It is designed for building web applications and APIs.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Phusion Passenger is a free web server and application server with support for Ruby, Python and Node.js.
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.
WhatsApp Business is a free to download app available on Android and iPhone using which businesses can connect with their customers.