Free antivirus software can do a surprisingly decent job -- as long as you don't want any 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). You'll also need to do without some features that can be helpful features and are found in paid software (like protecting you on Facebook and Twitter, or when you're paying online with your credit card).
Free software also 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.
Panda Free Antivirus 2015 (Free) is an Editors' Choice at PCMag.com. AV-Test.org gave it a perfect score for protecting Windows 8.1 systems in a test it ran in Sept./Oct. 2014 -- equal to the best paid product. Panda didn't fare as well when it came to system impact or usability, and exceeded the industry average when it came to incorrectly identifying legitimate software as malware. At AV-Comparatives.com, the Panda antivirus engine scores well in tests gauged to measure effectiveness (Advanced or Advanced+ ratings), but only the lowest acceptable rating (Standard) when it comes to its impact on system performance. User reviews at Download.com are solid, and it earns a 4.5-star rating from the editors there.
Panda Free Antivirus offers many of the same protections as the paid version of Panda. That includes real-time antivirus and antispyware scanning, and the monitoring of files and processes to spot brand new viruses based on their behavior. It can also warn you off of malicious web sites. There's also a tool that lets you create a bootable rescue USB drive that can scan and clean an infected computer. Download.com's Eddie Cho warns that it pays to pay attention during install as default options can switch your preferred search engine and browser start page -- of course, that type of annoying behavior is part of lots of free software, and even some paid products. Beyond that, installation is easy, PCMag.com reports, and the user interface is clean and modern.
There are lots of other free antivirus programs worth considering. Avast! Free Antivirus 2015 (Free) is recommended by one independent reviewer, and is a Download.com Download Pick. It's also adored by users. All versions earn an overall score of 4.5 stars following more than 26,500 user ratings at Download.com, and that's outstanding compared to the feedback that most security software receives at that site; the current version scores similarly well following more than 300 ratings. At Amazon.com, more than 8,700 users team up to award Avast! a score of 4.6 stars.
Lab test results for Avast! are kind of all over the place, but largely point to a product that performs better than most free antivirus software, though a step behind the very best paid products. AV-Test.org's results reveal that Avast! Free Antivirus 2015 performs on a par with other products, free and paid, when it comes to malware protection, and above average when it comes to usability and freedom from false positives. However, it extracts a higher than industry average hit when it comes to system slowdowns. At AV-Comparatives.org, Avast! does a good job of correctly identifying malicious files, but its false-alarm rate is literally off the charts -- the exact opposite of the finding at AV-Test.org. Otherwise, the software earns solid Advanced or Advanced+ ratings when it comes to malware prevention and minimal impact to system resources -- the latter another contradiction to the AV-Test.org findings. Dennis Technology Labs gives Avast! an AA rating, its second highest score.
One place where Avast! has an advantage over most free and some paid antivirus software is that it is relatively feature rich. The big plus is the ability to analyze your entire network for security holes, including your router and any wireless devices. Browser Cleanup goes beyond just cleaning out caches and cookies by letting you remove unwanted toolbars and extensions you may have unwittingly let third-party software install. Software updater looks for new versions and patches for popular software.
Elsewhere in this Report:
Best Reviewed Antivirus Software: Keep your computer safe from evil-doers with a top-notch antivirus program. The best programs for PC's and Mac's are named, including some effective options that are absolutely free.
Best Antivirus Software: Keep your PC malware free with these top paid antivirus programs. All offer full protection, are easy to use, and won't drag your system down.
Best Mac Antivirus Software: Yes, Macs need antivirus protection, too. These are top choices. Better still, all are free. We touch on security software for mobile devices as well.
Buying Guide: Not sure where to start to find the best antivirus software. Our editors fill in the blanks to help you make the right choice for your needs and your budget.
Our Sources: The recommendations in this report are based on expert reviews, independent testing, and user feedback. These are the sources we relied on, ranked in the order of their expertise and helpfulness.