Some of my programs use Microsoft HTML help described at https://docs.microsoft.com/en-us/previous-versions/windows/desktop/htmlhelp/microsoft-html-help-downloads
HTML Help Workshop
htmlhelp.exe
Download: https://drive.google.com/file/d/1-EzugNZG_lRRxkCQp2O8rUtMajmV7VBe/view?usp=sharing
HTML Help Documentation
HelpDocs.zip
Download: https://drive.google.com/file/d/1UNCn2y7vsXsjIdniYbZ1QyQH7jrvQQH_/view?usp=sharing