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
HelpStack - Open Source mobile help framework to support iOS and Android app users.
Zoho Desk - Industry's first context-aware Helpdesk Software
Chat Center - Chat with one click, no matter what messaging app you use
Salesforce Service Cloud - Service Cloud integrates customer service with social networks and provides a self-service customer portal and knowledge base system.
Helpshift - Helpshift is an in-game customer support platform that enables mobile apps to improve customer experience, drive higher ratings and increase retention.