Our best free antivirus round-up has been fully updated.
Staying loyal to the trusty built-in Windows Defender keeps you safe to a certain extent but when it comes to covering your PC with a layer of protection that is a worthy of the modern age you need to go beyond that. Remember, independent testing has shown, in the past, that Microsoft's layer has very poor protection rates (its miss rate stands at around 17%), and as such you must look elsewhere.
Luckily paying through the nose for this type of protection is no longer the status quo and there are scores of different programs offering protection that is more than adequate. So if you no longer want to pay for the privilege of protecting your valuable piece of hardware, read on - we've picked out five of the best free antivirus engines to deliver great security at no cost.
1. 360 Total Security
If you're looking for a standalone antivirus package then 360 Total Security might seem a little overweight. It provides antiphishing support, online shopping protection, network threat blocking, hard drive clean-up tools, a Windows update checker, and more.
This feature overload does make for a relatively complex interface. It's not always easy to operate, and if you run into problems there's no significant documentation to help.
Still, what makes the suite interesting is that it uses no less than four antivirus engines. Install it and you can be protected by Bitdefender technology (an excellent commercial engine), Avira (probably the best of the free offerings), and two further engines of Qihoo's own.
This isn't just some marketing gimmick, either. Independent labs including AV-Test, AV-Comparatives and Virus Bulletin regularly rate Qihoo 360 as one of the top two antivirus products.
Our tests also showed some problems. 360 Total Security took anything up to twice as long to scan our system than some of the competition, presumably because of the four engines. It also returned more false positives, just as we expected (each engine will generate a few of its own).
Surprisingly, however, all this bulk didn't weigh down our PC in normal use, with 360 Total Security having minimal effect on system speeds. VB100 and AV-Comparatives testing also suggests the suite has little performance impact.
360 Total Security is far from perfect, and if you're looking for a simple antivirus engine to run alongside other security tools then it'll probably be too much. But if detection rates are your top priority then the package is hard to beat.
2. Avast Free Antivirus
While free antivirus software won't cost you anything to download, you might sometimes find you'll pay in other ways. Install Avast Free Antivirus and it'll also equip your PC with Google toolbar, unless you're paying attention and clear the relevant checkbox.
The advertising doesn't stop there. By default Avast Free Antivirus scans for "performance issues" (junk files, unnecessary apps) as well as malware. It then displays any problem areas in a banner, but won't fix any of them unless you buy Avast's GrimeFighter.
Fortunately you don't have to live with this. Avast Free Antivirus has an excellent interface – it's clean, clear and configurable – and in just a few clicks you can set it up to avoid the pointless GrimeFighter scan.
The testing labs give Avast mid-range scores, as we write; typically the company outperforms AVG, but doesn't quite match the power of Avira.
Still, the package does rate highly when dealing with zero-day threats, and in our experience gives very few false positives.
Crucially, it's also better than most at blocking malicious URLs, which means you're less likely to encounter malware in the first place.
Useful extras include checks for network security holes (like a router still using the default password), while the Software Update highlights missing software patches and installs them with a click.
Better still, everything is very configurable. If you're not quite happy with Avast's Web Shield, for example, you can change what and how it scans, tell the program to ignore particular URLs, processes, MIME or file types, and define exactly what to do if it finds something.
Avast Free Antivirus may not quite offer the best protection, then, but its interface is one of the best around, and experienced users will appreciate its extreme configurability.
3. AVG AntiVirus Free
If you've ever wondered why security companies give away free software, AVG AntiVirus Free gives you the answer. They're a great marketing opportunity, and the program comes with a host of ads, "Go Pro" buttons and website links which try to persuade you to upgrade.
Still, AVG AntiVirus Free does at least spend most of the time out of sight, running in the background, so this may not matter very much. And the program does have other compensations.
An excellent scheduler automatically runs scans at regular intervals, on certain days of the week or month – maybe when your system boots. It's just as easy to schedule program and definition updates, ensuring these won't tie up network bandwidth when you need it most.
The program's AVG Turbo Scan feature supposedly improves scan speeds by "following the order in which files are saved to the hard drive". That sounds like marketing speak, but our tests suggest otherwise, with AVG AntiVirus Free achieving some of the fastest scan times in this group.
Accuracy is more important, of course, and the story there is more uncertain. The program returned only average detection results in our small trials, and the independent testing labs also aren't too impressed. AV-Comparatives' 2014 Real-World Protection Tests typically placed AVG around the middle of their 22 contenders, although they do also show one significant plus: the program generates very few false positives.
Put it all together and AVG AntiVirus Free only just scrapes into our top five. The program's speed, configurability and good antiphishing results are real advantages, though, and if you're an AVG fan then it may be worth a try.
4. Avira Free Antivirus
Some security companies spend a great deal of time and effort on interface design, but Avira isn't quite so concerned. Sure, Avira Free Antivirus adds a graphical launcher to your system tray, but the core program looks plain, ordinary, and a little dated.
Fortunately Avira scores where it matters. The company seems much more interested in substance than style, and the end result is one of the best security freebies around.
The program is loved by the testing labs. Whether you check out AV-Test, AV-Comparatives or VB100 reports, Avira technology almost always scores very highly. And that's not only in relation to free software. AV-Comparative's December 2014 Real-World Protection Test ranked the program fifth out of 22 mostly commercial contenders, with the same 99.4% protection rate as the highly-rated Bitdefender and Kaspersky. (That's a typical score, not a fluke – sometimes Avira tops the list.)
If you're looking for an easy life then you can leave the program alone, and it'll do its work almost entirely automatically. But expert users get plenty of fine control. There are options to protect the Hosts file, block autorun, scan archives (including a configurable recursion depth), monitor network drives, set the file types to be scanned, even password protect your Avira installation so others can't mess with your settings.
Avira Free Antivirus has a distinct shortage of bonus extras, which might be an issue for some. The "Firewall" options add little (they configure the standard Windows firewall, rather than adding anything new), and even basic web protection requires a separate browser extension.
Still, for us, Avira's stripped-back design is a plus, as it makes it easier to add other security tools without conflicts. Factor in its very accurate engine and Avira is our pick of the free antivirus crop.
5. Panda Free Antivirus
Panda Free Antivirus makes a great first impression, with its colourful Windows 8-style interface giving easy access to the program's many features.
We were surprised to find the main screen is configurable, too. If you're unhappy with the layout of the tiles then you can drag and drop them around, delete some or add others.
The verdict on the core antivirus engine is a little less clear. We found it delivered great detection rates in our own small-scale tests, but scanning speeds were a little below average.
The independent testing labs also have some doubts, with AV-Comparatives in particular showing protection levels falling a little towards the end of the year. But that's still good enough to justify a top five position, and the test reports also highlight some other positives (the package raises very few false alarms).
A useful set of extras start with the URL filter, which does a solid job of preventing access to malicious sites. The USB Vaccine feature tries to protect your USB keys from some infections, while Process Monitor is a Task Manager-like tool, displaying running processes, their open HTTP connections, and highlighting likely dangers.
If all this fails then Panda's Rescue Kit could be a lifesaver. It's able to download and run Panda Cloud Cleaner, which is great for catching the very latest malware, or you can build a bootable USB key to remove the most stubborn of threats.
Panda Free Antivirus isn't quite as powerful as the market leaders, but it still offers very capable protection and some valuable bonus features. If you're looking for a simple package which anyone can use then it's a sensible choice.