Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
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
Outbound Apps by Intercom - Embed apps right inside your messages
HelpScout - Help Scout is a simple, straightforward way to provide excellent support
Intercom App Store - Integrate with Intercom and grow your business