Carrot quest is a customer engagement and communication platform that aids businesses in improving interactions with users and customers through targeted messaging, in-app messaging, live chat, email campaigns, and user behavior tracking.
Drupal is a free and open-source web content management framework.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.