iAntiVirus - free malware protection for your Mac.

As we all know, Mac is a really safe OS but the truth is that no platform is immune to any kind of malware. Even the Mac OS X. However, the risk on infection on Mac is really low, since most of the attacks are directed against Windows. So there isn't a real necessity to use an antivirus software if you're on Mac, but if you have "terrifying" experiences from Windows, you may use one.

iAntiVirus is a free antivirus solution for Mac, offering most of what a regular user needs. As the official site says, this application offers powerful malware protection (viruses, worms and trojans) - detection and removal-, spyware, adware and dialer protection, real-time protection via "IntelliGuard Real-Time Protection", free support by community and free "Smart Updates".

It offers just a basic interface, and uses very little resources as I even don't feel it working in the background. These are what the free version offers. If you need it for business and commercial purposes, 24/7 dedicated and phone support, paid version is also available.

Consult the official site for more details: http://www.iantivirus.com/.