HelpStack - Open Source mobile help framework to support iOS and Android app users.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Chat Center - Chat with one click, no matter what messaging app you use
HiOperator - HiOperator is a virtual assistant that answers phone calls, chats with customers, provides in-app help, takes orders, and provides support.
Helpshift - Helpshift is an in-game customer support platform that enables mobile apps to improve customer experience, drive higher ratings and increase retention.
GetHuman - Find customer service numbers fast