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.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Phusion Passenger is a free web server and application server with support for Ruby, Python and Node.js.
WhatsApp Business is a free to download app available on Android and iPhone using which businesses can connect with their customers.