iChm icon Robin Lu has released iChm, a Cocoa-based CHM reader for Mac OS X with Webkit rendering, a slick tabbed interface and a bookmark system that not only allows you to store links to favorite topics in the current file, but also keeps track of your bookmarks across multiple files like in a regular Web browser.

When you bookmark a topic, you can assign tags which allow you to quickly access topics in any CHM file based on the keywords you have specified.

While the concept of tagging is hardly new, the feature is unique to CHM viewers on the Mac, and can be especially useful for help developers looking for a simple means of flagging open issues in topics — just add a FIXME tag to keep track of those pesky output bugs while you tweak your WebWorks stationery.

Unfortunately, iChm shares a shortcoming with many other Mac CHM viewers: the current version (1.1.1) offers no support for the index, which is an essential component of any well-built help system. With a little luck and a bit of persuasion, perhaps Robin can be convinced to add this feature in a later version.

It wouldn’t take much to make this the best CHM viewer available on the Mac — so many of the others were apparently released as one-hit wonders and have not been actively maintained in years.

2008-08-27 Update: Version 1.2 now includes index support.

2008-09-04 Update: Version 1.3 now allows you to search the index.