UPDATE: Most antivirus software will stop infection by the widespread variants of the WannaCry ransomware, and our best picks will almost certainly story new versions that haven't been seen before. For more on WannaCry and what to do about it, check out our WannaCry FAQ.
Many Windows users believe they don't need to pay for antivirus software, and most Mac and Android users think they don't need protection at all. Windows' much higher profile makes it the biggest target, yet the truth is that OS X/macOS and Android are equally vulnerable to malware.
We believe it's worth paying for Windows antivirus software, because even the best free software leaves out protection features we consider essential. You don't have to spend a lot. Many antivirus products are sold online for much less than their list prices. Mac and Android users have other options; one of our favorite Mac AV products costs nothing, and most Android security apps have free versions.
How We Tested
Our evaluations were based on an antivirus product's interface, performance, protection and extra features. Was the product's interface intuitive and user-friendly, or did it make it hard to find important tools? How badly did malware scans slow down the computer's performance? How good was the program at detecting and removing malware? Does the program have any additional tools, and are they useful?
All of our Windows tests were performed on the same Asus X555LA laptop running 64-bit Windows 8.1 (later upgraded to Windows 10), with an Intel Core i3 processor, 6GB of RAM and a 500GB hard drive containing 36GB of files. To assess a program's impact on system speed, we used our custom OpenOffice benchmark test, which matches 20,000 names and addresses on a spreadsheet. The longer it took the laptop to finish the test, the heavier the performance impact. For smartphones, we used the Geekbench 3 benchmarking app.
Our Mac evaluations were conducted on a late-2013 MacBook Pro running OS X El Capitan 10.11. The Mac had a 2.6-GHz Intel Core i7 CPU, 8GB of RAM and 23GB of data on a 512GB SSD. For Android, we used a Nexus 6P smartphone running Android 6.0.1 Marshmallow.
For malware-detection scores, we've turned to two independent testing labs, AV-TEST of Germany and AV-Comparatives of Austria. Each lab regularly subjects the major antivirus brands' flagship products to stress tests involving hundreds of previously unseen pieces of malware, with AV-TEST adding 20,000 instances of known malware. We use the latest results from both labs.
Windows Antivirus Software Types
Most antivirus makers have three or four tiers of Windows products, with each price bump adding extra features, such as parental controls or cloud backups. But because each company uses a single malware-detection engine for all its Windows antivirus software, the cheapest item -- even a free one -- in any product line usually finds malware just as thoroughly as the priciest.
Not all users will need premium suites, or even midrange products. If you don't have kids, or if you already have backup software, the basic product may be enough.
The least-expensive paid Windows antivirus products, which generally list from $40 to $60 per year depending on the number of PCs covered, have the essentials. Definition updates and scans are automatic; websites and email attachments are screened, and the products are mostly easy to use. Some basic AV programs toss in extra features, such as file shredders or system optimizers, that are normally found in pricier products.
These products usually list from $60 to $80 per year. They generally build on the basic packages by bundling in parental controls and a two-way firewall to catch outgoing data, although many add other features. But for the full feature set each brand offers, you'll have to pony up for the premium products.
Top-tier packages are often called suites because they do much more than catch malware. They might also offer file encryption, secure online storage, a password manager or an ad blocker. As most suites cover multiple devices, they also frequently bundle in licenses for Mac and Android antivirus software. For all this, you're meant to pay between $80 and $100 per year — but as with all paid antivirus software, steep discounts can often be found online.
Free Windows antivirus products usually offer only bare-bones protection. Malware updates and scans must often be manually initiated, and there is seldom any protection against malicious websites or email attachments. We can recommend some free Windows antivirus software, but please don't rely on Microsoft's own products (Windows Defender/Microsoft Security Essentials). Those two products are getting better, but for now, they simply don't stop enough malware.
Despite what Apple's marketing has historically implied, Macs do get infected, and the amount of Mac malware has risen with Apple's share of the personal computer market. But there's less money to be made in the Mac antivirus market than in the Windows one, and the products are less standardized. Some Mac antivirus products are free, and some are paid. Of the products we recently evaluated, our No. 2 choice was free.
Every Android device, whether smartphone, tablet or TV stick, should have antivirus software. Usually, that software comes with an all-encompassing security app that also includes anti-theft and remote-locating features, and many apps have both a basic free version and a premium version with more features.
The free versions of the Android security apps we reviewed are pretty solid. The paid versions, which cost between $15 and $30 per year, range from being just a bit better than the free ones to becoming practically separate products, with a wide range of capabilities. You'll have to decide what you need and select accordingly.
iOS Antivirus Apps
A lot of people want iOS antivirus software for their iPhones and iPads. The truth is that such software doesn't exist. Apple won't let third-party apps examine other iOS apps, or even inspect new apps as they're installed. Anything that claims to be antivirus software swiftly gets kicked out of the iTunes App Store.
Many major antivirus vendors, including F-Secure, McAfee, Norton and Trend Micro, do have "security" apps in the App Store. But these check web links for known malicious sites, locate lost devices or pretend to protect your privacy. None scans an iPhone for malware.
There has been real iOS malware that affects non-jailbroken devices, but it's very rarely cropped up. In each instance, Apple has pushed out a new version of iOS to stop the malware in a matter of days or weeks. Generally, if you keep your Apple mobile device updated to the latest version of iOS, you should be safe.