If so are there any good ones for free?
OS X Mountain Lion (10.8.3)
No, you really don't. See, also:
Helpful Links Regarding Malware Protection
An excellent link to read is Tom Reed's Mac Malware Guide.
Also, visit The XLab FAQs and read Detecting and avoiding malware and spyware.
If you require anti-virus protection I recommend using ClamXav.
If you choose to use anti-virus software on your Mac (see my Mac Malware Guide), you should only use one of the free ones, in my opinion. Commercial ones can, in many cases, have worse detection rates than some of the free ones, and offer a lot of extra features that you really don't need.
If you decide using AV software is best for your needs, then there are several free ones that do fine. A couple of these are Sophos Home Edition and ClamXav. Norton's iAntivirus is an alternative, but so far it does not have built-in autoupdate features so its definitions can be months behind others (I believe this is due to restrictions for App Store programs being updated through the App Store, but I'm not sure).
Keep in mind that Apple also includes a rudimentary malware scanner in OS X called XProtect, that runs behind the scenes; however, it is only automatically triggered by certain applications that download files (not all). I personally wouldn't rely upon it solely as the only malware scanner to use.
it does not have built-in autoupdate features so its definitions can be months behind others (I believe this is due to restrictions for App Store programs being updated through the App Store, but I'm not sure).
Other anti-virus software available through the App Store, such as VirusBarrier Express and BitDefender, don't suffer from the same problem, so it's definitely not a limitation of the App Store. It's all down to incompetence at Symantec, in my eyes.
Do we really need antivirus for a mac?
