Compatible platforms: 10.4 (Tiger) and 10.5 (Leopard); if you’re running 10.6 (Snow Leopard), you’ll need to grab ClamXav version 2.0, just note that it’s in beta as of this writing; folks who are still running 10.2 and 10.3 aren’t completely left out in the cold, but due to the developer’s (completely understandable) limited resources, the virus scanning engine is slightly out of date.

Version highlighted in this post: 1.1.1

“Wha?!” you say. “Fer realz!” I say. Today, we’re looking at a Mac anti-virus app. And as always, it’s completely free.

News arrived last week that the brand new OS X (10.6 a.k.a. Snow Leopard) will contain a malware blocker. Soon after, though, word dropped that it’ll only cover two pieces of malware and would be pretty limited in terms of which programs it works with. Fortunately, even that is sufficient for most Mac users.

But if you’re interested in something that packs a bit more oomph, ClamXav is here for you. ClamXav is a litter-mate of two other great programs, ClamAV (the UNIX/Linux anti-virus scanner) and ClamWin (the open source Windows AV scanner). Their shared underlying scanning engine is what makes them siblings. The engine is the part of an AV program that tells it what patterns within a file are dangerous and which virus that pattern matches.

My favorite thing about all of the ClamAV-based apps is that they don’t insist on sitting on your machine running all the time. That’s especially useful for Mac users since stumbling across a threat is so rare. It’s much nicer to have those system resources open for regular computing and just running the AV program from time-to-time.

There’s one quick caveat that I always have to mention with the ClamAV apps, though. The first time you fire up the program, before you even run a scan, go into the preferences and under ‘General’ make sure that there’s a check mark next to ‘Quarantine infected files to:’, and verify that there’s a quarantine folder set. If that’s not done, the program will just run the scan and come back and tell you, “Hey, I found something!” But not actually do anything about any of the problem files.

With the tiny number of viruses that affect the Mac, just having ClamXav around to run periodically is plenty and should keep you way ahead of the curve and sleeping well at night.