What are some alternatives?
HelpNDoc - What is HelpNDoc ? Easy to use yet powerful help authoring environment which can generate various documentation formats from a single source.
MadCap Flare - Documentation for Any Audience, Language or Format
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.
CHM Decoder - CHM Decoder may decompile your CHM file (Compiled Windows HTML Help) or e-book and extract all...
Adobe RoboHelp - Adobe RoboHelp empowers organizations to deliver engaging help and policy content across mobile devices, formats, and platforms.
ExtraCHM - A fully featured reader for Compiled HTML (chm) documents.