Zendesk - Zendesk is a beautiful, lightweight help-desk solution.

Invision Community - Invision Community is a flexible, integrated set of apps for building communities on the web.

Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community

XenForo - Intuitive. Social. Engaging. Fast. XenForo brings a fresh outlook to forum software.

HelpScout - Help Scout is a simple, straightforward way to provide excellent support

Mobilize - Mobilize is a scalable messaging app built for large groups.