What are some alternatives?
Dr.Explain - Dr.Explain software is a help file authoring tool.
Readymag - Readymag is a comprehensive solution that allows you to design web publication, magazines, presentations, websites, and all the other publications.
HelpSmith - HelpSmith is a help authoring tool to create CHM HTML help files, manuals, and PDF documents.
Zmags - Zmags provides solutions create and publish web experiences instantly.
Adobe RoboHelp - Adobe RoboHelp empowers organizations to deliver engaging help and policy content across mobile devices, formats, and platforms.
SPIP - Système de Publication pour Internet