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

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

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

NationBuilder - The world's first platform for leaders, handcrafted from scratch to help you grow your community and lead them to action.

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

vBulletin - Build a community website with the leading forum software, vBulletin 5 Connect, or in the cloud on vB Cloud!