Taiga - Project management platform for agile developers & designers
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
TargetProcess - Agile Project Management Web Application
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
Craft.io - All-in-one product management software for entire product lifecycle
HelpScout - Help Scout is a simple, straightforward way to provide excellent support