UseResponse - Open-source, self-hosted customer feedback software, live chat and helpdesk system that you can install on your server. Organize documentation using knowledge base and get feedback from social networks with centralized system
Marketo - Marketo's powerful marketing automation software helps marketers master the art & science of digital marketing to engage customers and prospects.
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.
HubSpot Marketing Hub - HubSpot is a cloud-based inbound marketing software that allows businesses to transform the way that they market online.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Ortto - Journeys made simple. Your customer data, messaging and analytics working together.