Dr.Explain - Dr.Explain software is a help file authoring tool.
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Document360 - Self-service knowledge base software focused on SaaS Products & Enterprise Software Projects.
Salesforce Service Cloud - Service Cloud integrates customer service with social networks and provides a self-service customer portal and knowledge base system.
WinCHM - Creating CHM file, Make CHM file, Web Help. WinCHM Pro - Help authoring software (CHM, WebHelp, DOC, PDF) . With this powerful tool you can not only create chm file from scratch, but also convert a set of existing HTML files to a chm file.
Sitecore - Sitecore A/S has produced the Sitecore content management system since 1999.