Best free antivirus software 2015

Keeping your PC malware-free doesn't have to be expensive

Avira Free Antivirus

Our best free antivirus round-up has been fully updated.

Reliable antivirus protection is a must-have for every PC. You know this. We know this. But so do the security companies, which is why covering all your devices can become very expensive.

You could ditch your paid products and hope Windows Defender will keep you safe – but as independent testing shows very poor detection rates (it typically misses one threat in six), that's probably going to be a serious mistake.

However, there are plenty of free antivirus solutions around which do deliver solid protection, and are just as capable as their commercial cousins. So if you're tired of those annual subscriptions, 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.

360 Total Security
360 Total Security takes its time over scans, but finds most threats

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.

Avast Free
Avast Free is easy to use – even beginners will feel at home right away

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.

AVG Free
AVG Free looks great, but be careful where you click – there are ads everywhere

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.