A quick search for Mac CHM viewers yields a handful of open source & shareware apps which provide Mac users access to Windows help files in the Compiled HTML Help (CHM) format.
A few older shareware apps such as Chimp and CHM Viewer are only available in PowerPC versions and apparently no longer actively developed.
The remaining candidates are all free, open source software and available as universal binaries for PPC & Intel Macs. Each does pretty much the same thing — more or less successfully — though none of them quite manage to support all of the features CHMs provide in their native Windows environment.
Here’s a short list of a few pros (+) & cons (-) that appear at first glance:
+ Beautiful HTML page rendering via Apple’s WebKit browser engine
- Chokes on some large & complex pages
- No search, index or favorites support
+ Functional search, index & favorites (bookmarks)
- Only basic HTML rendering, poor table/CSS support
+ Supposedly supports ToC, Indexing, Search and Favorites,
- Unreliable — index shown in test file is incomplete, odd CSS background rendering quirks
(should we read “Chamonix” as “shame on it”?)
For a more detailed — though somewhat outdated — comparison of xCHM & the now-defunct CHM Viewer, see this Mac OS X Hints article.