What are some alternatives?
When comparing WinCHM and Kchmviewer, you can also consider the following products
HelpNDoc - What is HelpNDoc ? Easy to use yet powerful help authoring environment which can generate various documentation formats from a single source.
CHM Editor - Best solution to edit CHM files
Helpinator - WYSIWYG, single source, multiformat, multilingual help authoring tool with screenshot capture and annotation. CHM, PDF, WebHelp, QtHelp, JavaHelp, OracleHelp, WordPress. 249USD.
Chmox - Chmox is a free (of charge), open source application for OS X which lets you read Windows Help...
xchm - xCHM is a cross-platform GUI front-end to chmlib, with borrowed bits from Pabs' chmdeco project.
CHM Reader Pro - CHM Reader Pro is can read CHM file and Convert CHM to PDF.