Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
HelpNDoc - What is HelpNDoc ? Easy to use yet powerful help authoring environment which can generate various documentation formats from a single source.
Service - Customer service issues solved for you, on demand, for free.
Dr.Explain - Dr.Explain software is a help file authoring tool.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
CHM Editor - Best solution to edit CHM files