You want security software that's as close to perfect as possible. After all, if just a single piece of malware slips through your defenses, it can wreak havoc on your PC. The question is, how close to perfect is free antivirus software?
According to our testing, some free antivirus programs do an admirable job of detecting, blocking, and removing malware, but others don't have what it takes to protect you.
For this roundup, we once again teamed up with AV-Test, a well-respected antivirus-software testing lab, to put nine free antivirus programs through their paces. Applying a rigorous battery of tests, AV-Test evaluated all of the packages to see how well each one can withstand both brand-new malware and older baddies, and how well each can clean up a malware mess. In addition, AV-Test performed a number of system-speed tests to determine how much each program will drag down a PC's performance. Finally, after installing the programs, we evaluated how easy each one is to use.
What Do You Get for Free?
Most free antivirus programs are pretty basic: You get the ability to scan your PC for malware when you want to, and most of the products will also continually monitor your PC for malware as they run in the background. But most of them don't include a firewall or extra features like parental controls. (One exception: Comodo's free Internet Security Premium does bundle in a firewall.)
The biggest drawback to going free: Your support options are generally limited. Most free programs offer a message board where users can discuss problems, but these boards don't provide professional support. You can find exceptions, however. Comodo, for example, includes a version of its GeekBuddy software, which lets you work with a Comodo technician to fix issues you encounter.
Which Package Is for You?
AVG Anti-Virus Free Edition 2012 came out on top in our testing. It's fast, it blocks brand-new malware effectively, and it cleans up infected PCs efficiently. Avast Free Antivirus 7 and Panda Cloud Antivirus 1.5 round out the top three.
If you're looking for something that can serve as a supplement to your current antivirus software, we review three possibilities; of those three, PC Tools Threatfire is a good option: It was the best all-around at stopping brand-new malware attacks in our testing. Threatfire relies solely on what's called behavioral analysis—how programs behave on your PC—to identify malware, whereas most traditional antivirus apps use either malware definition files or a combination of technologies to stop threats. Since Threatfire is primarily intended to stop malware before the invader causes a problem, you should be sure to install it on a clean PC.
Read how we rate antivirus software. Click on the links below to download your choice of packages, and click on the screens, including the chart thumbnail at right, to enlarge them. (The chart shows how well the seven packages reviewed performed in our tests.)
The reviews here appear in order of scoring.
AVG Anti-Virus Free Edition
Our top pick, AVG Anti-Virus Free Edition 2012, performed well in virtually all of the tests we ran.
In our real-world malware detection tests, which evaluate how well an antivirus package will block brand-new threats, AVG's freebie blocked 85.7% of the samples, tying for the best result among the programs we tested. It detected 98.7% of the more than 129,000 samples of malware from the past four months in our malware "zoo" test. That's a good score, although a bit short of the best results we've seen.
AVG was at the top of its class in disabling active malware infections: On our test PC, it detected and disabled all malicious software, and removed all traces of malware two-thirds of the time.
AVG also scans a PC relatively quickly. When we directed it to check 4.5GB of data, it sped through the job in 1 minute, 35 seconds, the third-fastest time in this test and only 4 seconds slower than the fastest. Its on-access scanner—which runs when you open or save a file—took 4 minutes, 55 seconds to go through the same amount of data, about average for the programs we looked at.
I like AVG's main interface, though its advanced settings could intimidate some users. Apart from that caveat, if you're looking for solid, fast PC protection, look no further than AVG.
Avast Free Antivirus
Avast's freebie finished second in this year's roundup. Avast Free Antivirus 7 mostly excelled in protecting against malware, it has a versatile interface, and it sped through our battery of malware tests.
Avast's defenses were weakest at blocking new real-world threats: It caught just 78.6% of them—not outstanding, but slightly above average. Avast did far better at stopping well-known malware, detecting 99.1% of samples in our zoo test—a very good showing. This package cleans up malware infections effectively, as well. It detected all the malware residing on our test PC, and disarmed the invaders 93% of the time, tying for second-best in this test. The utility also removed all traces of infections two-thirds of the time.
The Avast offering won't slow your PC down much. It completed the on-demand scan test in 1 minute, 34 seconds, for second-best in the group; and it finished the on-access test in 4 minutes, 16 seconds, good enough for third-best.
Avast's interface has a lot going on—advanced users will find many settings to toggle. Despite this complexity, it is nevertheless friendly enough that it shouldn't scare away less-geeky users.
Panda Cloud Antivirus
If you think setting up antivirus software should be as simple as possible, Panda Cloud Antivirus 1.5 is for you. Panda stops malware well, and its extremely easy-to-use interface is great for those people who don't want to tweak all sorts of settings.
Panda blocked 85.7% of new malware, the same score as AVG. And the Panda freebie outperformed AVG in the malware zoo test by detecting 99.94% of the samples.
Panda did only a so-so job at cleaning up infections. It detected all active infections on our test system, and disabled 87% of them, about average on this test. It completely removed infections 60% of the time, also about average.
Panda's program was far from speedy in some tests. It slowed the copying of files over the network considerably, and its scan speeds were among the slowest we saw: It completed the on-demand test in 6 minutes, 10 seconds, and in the on-access scan test it took 7 minutes, 25 seconds.
If you value simplicity over speed, however, Panda Cloud Antivirus, given its success in detecting malware, makes a good choice.
Avira Free Antivirus
Avira Free Antivirus 2012 is fast and is unlikely to scare you with warnings about legitimate files, but it is also worse than average at detecting malware, and its interface is overly complicated.
Avira blocked 70.4% of the samples of new viruses in our real-world test, slightly worse than average for the tools we tested. It also lags in disinfection: Though it found all active malware infections on our test system, it disabled only 80% of them, another worse-than-average showing.
I'm not a big fan of Avira's interface. Its overview panel is better than in previous versions, but the interface remains too technical in places. Also, I noticed that Avira occasionally displays ads.
Avira's results weren't all bad, however. It detected 99.7% of known malware samples in our zoo test, and it was one of only two free antivirus programs we tested that didn't mistakenly label legitimate files as possible malware. Its on-demand scan time of 1 minute, 31 seconds was the best in our testing, and its on-access scan time of 4 minutes, 54 seconds was respectable.
Using Avira will by no means leave your PC completely open to malware, but you should consider the higher-scoring AVG, Avast, or Panda first.
Next: Microsoft Security Essentials, and more, plus supplementary tools.
Microsoft Security Essentials
Microsoft Security Essentials 2.1, our fifth-place finisher, is something of a mixed bag. I like its interface, and it is reasonably good at cleaning up infections, but it falters at stopping new malware, and it plods through its chores.
Security Essentials' user interface is particularly straightforward—perfect if you don't want to waste time messing around with your antivirus software.
Microsoft's program cleans up malware infections quite effectively: In our tests, it identified all active infections on our machine and disabled over 93% of the malware. It removed all traces of malware 80% of the time—better than any of its competitors in this roundup. In addition, it was one of the two free antivirus applications that didn't mistake a single safe file for malware.
While Security Essentials excels at removing malware from a PC, it doesn't do as well at keeping dangerous code off a computer in the first place. It fully blocked 71.4% of new malware in our real-world tests, slightly worse than average. In our zoo test, it detected 97.0% of known malware samples. With that result, it lags the competition—some packages detected over 99.9% of samples.
Security Essentials didn't unduly slow overall system performance, but it performed a good deal worse than average in file-copy tests and app-installation tests. In scan speeds it also fell behind the pack: Its on-demand scanner completed our virtual obstacle course in a worse-than-average 3 minutes, 56 seconds. The on-access scanner was poky too, clocking in at 6 minutes, 43 seconds.
While Microsoft Security Essentials has some good qualities, you would be better served by looking at some other options.
PC Tools AntiVirus Free
PC Tools AntiVirus Free 2012 has its strong points, but it was the worst of the field when it came to blocking new malware. In our real-world blocking tests, PC Tools managed to stop only 57.1% of malware samples, placing it well behind its competition in this roundup.
On the plus side, PC Tools detected 99.96% of known malware from the past four months. It is also one of the best free antivirus programs at disinfecting a PC. It detected all infections on our test system, and it successfully disabled 93% of the infections. It removed all traces of malware in 73% of the cases.
PC Tools AntiVirus Free didn't slow overall system performance much. Its results were mixed when we tested scan speeds, though: Its on-demand scanner completed our tests in a sluggish 4 minutes, 51 seconds. On the other hand, the on-access scanner finished in 2 minutes, 50 seconds, the second-best time of all the products we tested.
PC Tools is easy to use for the most part, and its screens are laid out nicely. One thing I found annoying, however, was that it pushed the paid version of the company's software at every turn.
Comodo Internet Security Premium
Comodo Internet Security Premium 5.9 has an accessible interface, and it comes with a firewall (it's the only freebie we tested that has one), but in both malware blocking and cleanup, it ranks behind other free antivirus products we tested. (Note: This link goes to the download for Comodo Internet Security 5.10 in PCWorld's Downloads library.)
Comodo's performance in our real-world tests was acceptable: It blocked 78.6% of new malware, slightly above average compared with other free antivirus programs. It partly blocked an additional 21.4% of attacks. But Comodo protected poorly against well-known malware. It detected 98.2% of zoo samples—though that may sound like a good score, only two products we tested performed worse.
Malware cleanup may be Comodo's Achilles' heel: It detected all infections, but it was successful in disabling malware only 80% of the time—quite low compared with the top performers. It left behind more malware remnants than any other product, too; it was successful in removing all traces of malware only a third of the time.
For the most part, Comodo had a light impact on PC performance, but it significantly slowed copying of files across the network. Comodo also took its time in scanning files for threats: Its on-demand scanner took 4 minutes, 31 seconds—the third-slowest result. Meanwhile, the on-access scanner required a staggering 13 minutes, 58 seconds to run, nearly twice as long as the next-slowest product. While its included firewall makes Comodo Internet Security Premium an attractive option, we'd suggest giving other freebies a look first.
Here are three products to consider as supplements to your main antivirus software.
PC Tools Threatfire
PC Tools Threatfire won't replace your existing antivirus software, since it won't effectively clean up malware that has already infected your computer. What it will do, however, is excel at preventing brand-new threats from infiltrating your system.
Because of the way Threatfire works, we were unable to test it against our malware zoo of known threats. Threatfire doesn't use traditional signature files; instead, it relies solely on behavioral analysis—that is, it identifies malware based on how the invader acts on your PC.
That technology should make Threatfire fantastic at ferreting out new malware, and our tests bear that out. The tool produced outstanding results when blocking malware in our real-world tests: It fully blocked 92.9% of malware, and partially blocked the remaining 7.1%, the best showing of any free antivirus app we looked at this year.
As mentioned, Threatfire falters at disinfection: It detected and disabled only about half of the infections on our test PC. Because of this, it's best to install Threatfire on a clean, malware-free system.