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

Dr.Explain - Dr.Explain software is a help file authoring tool.

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.

MadCap Flare - Documentation for Any Audience, Language or Format

Dokit - The solution for disseminating know-how: work instructions, procedures, knowledge base, documentation techniques, product support, wiki enterprise.

HelpScribble - HelpScribble is a full-featured help authoring tool for easily creating professional Windows help files from start to finish.