What are some alternatives?
When comparing WinCHM and HelpNDoc, you can also consider the following products
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.
Kchmviewer - Kchmviewer is a free, open-source CHM (MS HTML help) and EPUB viewer for Unix, Mac and Windows...
HelpSmith - HelpSmith is a help authoring tool to create CHM HTML help files, manuals, and PDF documents.
MadCap Flare - Documentation for Any Audience, Language or Format
Dr.Explain - Dr.Explain software is a help file authoring tool.