HelpScout - Help Scout is a simple, straightforward way to provide excellent support

HelpNDoc - What is HelpNDoc ? Easy to use yet powerful help authoring environment which can generate various documentation formats from a single source.

HelpDesk - HelpDesk is a powerful and affordable ticketing system and help desk software for effortless customer support. Get started for free, no credit card required.

ManualsLib - Just enter the keywords in the search field and find what you are looking for!

Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.

Manuzoid - Repository that includes user manuals for various products