CHM file type usually i found this used for the application manual purpose on Windows. I was searching for a CHM file reader for Mac to read a PHP manual file.
When you try to open .chm file on Mac OS X you will get this message:

So i found Chmox a very useful open source CHM file viewer for Mac.
Download CHM reader for Mac

When you run this dmg file this will asks you accept the agreement and finally creates a drive icon.

Now just double click the CHM file to read in Mac.

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