Free antivirus software can do a surprisingly decent job -- as long as you don't want many frills. Paid antivirus software still outperforms the free stuff, catching more malware and having fewer false positives (detecting and even removing "threats" that aren't there -- an error that can hurt your computer). Freebies also lack some helpful features you'll find in paid software (like protecting you on Facebook and Twitter).
Free software peppers you with ads, which can get pretty annoying as they nag you to upgrade to the company's premium (read: paid) versions. Still, if you're looking for no-cost, no-frills antivirus software, these programs are getting better and better every year.
Free antivirus programs from Avast, Avira and AVG all protect admirably against malware in professional tests. (All work better in tests than Microsoft Windows Defender/Security Essentials, the antivirus software that comes pre-loaded on Windows computers.) But adoring users boost Avast Free Antivirus 2016 to the top spot, with hundreds of rave reviews at Amazon.com and CNET's Download.com.
"An excellent choice for free antivirus protection," PCMag.com's Neil J. Rubenking says, awarding Avast Free Antivirus 2016 his Editors' Choice award. Avast performs admirably in three separate independent labs' tests, blocking 97 percent (or more) of malware without slowing down the computer. Dennis Technology Labs declares Avast "the best free solution," nearly as good as the best paid antivirus software. When bombarded with malware, Avast "defended many more times than AVG" (although both Avast and AVG free antivirus programs earn Dennis's top AAA rating).
Anti-phishing, especially, is Avast's forte. In one leading test, Avast Free Antivirus 2016 does a better job blocking phony websites than any other free program tested (including AVG, Avira and Windows Defender) -- and even better than several popular paid antivirus programs. "What a success!" Rubenking says. "Avast handily outperformed the phishing protection built into Chrome, Firefox, and Internet Explorer." Only a Norton full security suite and Bitdefender Antivirus Plus 2016 (Est. $35 per year for 1 PC), our Best Reviewed pick for paid antivirus software, did better. (Phishing websites are fake versions of real websites, constructed to lure you into providing your passwords, bank numbers, etc.)
Finally, Avast offers nice extras, including a password manager and router security scan, for free. Avast Free Antivirus 2016 wins TomsGuide.com's award for "Best Built-in Feature Set" among the freebies.
Other free antivirus programs have their admirers, too. AVG AntiVirus Free (2016) (Free) shares the PCMag Editors' Choice award with Avast; Avast blocks more malware, but AVG blocks more malware-hosting websites. Similarly, in another leading test, AVG AntiVirus Free (2016) finishes 2 percentage points ahead of Avast; AVG protects better against USB threats, but Avast proves quicker to update itself to detect the very latest malware.
TomsGuide.com prefers a third choice, Avira Free Antivirus 2016 (Free). Avira detects a bit more malware than Avast or AVG in tests at AV-Test.org and AV-Comparatives.org -- 1 percent more or so -- but even its TomsGuide.com fans admit that you'll notice your computer slowing down with Avira, unlike the light-on-its-feet Avast.
Lifehacker.com also now recommends Avira as the best antivirus app for Windows. Until recently, editors there recommended Avast -- but in February, they switched their pick to Avira, based on its scores at AV-Test.org and AV-Comparatives.org, as well as some pop-ups and other annoyances they noted with Avast.
PCMag.com hasn't tested Avira Free Antivirus 2016, but the 2015 version earned only a mediocre score there. "You can do better," Rubenking concluded, after Avira performed poorly on the anti-phishing test and only so-so at malware blocking.
In another leading test, Avira isn't a standout in any test category. It finishes close behind AVG and Avast, and just ahead of Microsoft Windows Defender.