On some occasions we will find that we can't open files in this format. For those cases you can use Chmox, a practical viewer that allows us to comfortably view CHM documents on a Mac computer.
Once you have installed Chmox, all you have to do is double click on any file in CHM format. At that moment, the viewer will open. The viewer splits the screen in two: on one side you can read the text and on the other we can access the different categories by using direct links.
The application includes other interesting features associated with this type of file such as sending a selected text by email, automatic reading, document editing, searching on Google, etc.
From now on, you won't need to worry about not being able to view help files in CHM format, thanks to Chmox.