UserVoice - UserVoice integrates easy-to-use feedback, helpdesk, and knowledge base management tools in one platform that empowers users to speak and companies to understand.

HelpStack - Open Source mobile help framework to support iOS and Android app users.

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

Helpshift - Helpshift is an in-game customer support platform that enables mobile apps to improve customer experience, drive higher ratings and increase retention.

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

KeyReply - Omnichannel keyboard for mobile teams to respond better and faster.