The free antivirus software companies AVG and Avast! are strikingly similar in many ways: Both are Czech firms offering hotly competitive antivirus software in multiple languages. They often receive similar ratings; each scored 15 out of 18 in tests conducted by the German lab AV-Test.org, for example. AVG and Avast!, experts maintain, are first-rate products in the free antivirus market -- free being the operative word. Commercial products continue to outperform their free competitors by catching more malware and having fewer false positives (detecting and even removing "threats" that aren't there -- an error that can hurt your computer). Many commercial antivirus programs also offer outstanding features and stronger online protections. Free software comes with ads, many of which aim to get you to upgrade to the company's premium (read: paid) programs. Still, if you're looking for no-cost, no-frills antivirus software, they're getting better and better every day; currently Avast! comes out on top.
Avast! offers free virus and spyware protections for PC and Mac users (the free Mac version is discussed in the next section). It has the most downloads of any free antivirus software and is a CNET Download.com Editors' Choice. Avast! scores well in lab tests at catching malware -- though it should be noted that paid software usually performs better, which is one of the pitfalls of free programs. Among other features, it uses customers' anonymous warnings to steer you away from potentially malicious websites. It's offered in a whopping 42 languages (as opposed to rival AVG's 22). Testing labs AV-Test.org and AV-Comparatives.org both certify and give Avast! solid ratings.
AVG Antivirus 2013 is still a favorite of some prominent testers like PCMag.com, though it's not as highly recommended as Avast!. AVG is fast, which isn't surprising given that the impact on system performance is usually minimal for free antivirus software. It has a Windows 8-friendly makeover with big tiles and touch-screen capabilities that reviewers adore, and provides strong malware removal, rootkit detection and basic protections against email and web viruses.
Worth noting: If you choose to download free antivirus software (nearly all are only available online) and are using Windows Vista or XP, CNET's Download.com warns that "you definitely ought to have a firewall upgrade."