The best free antivirus
Windows 10 comes with its own free antivirus in the form of Windows Defender. It's okay, but its threat detection rates aren't the best, and third-party security software offers lots of extra features to protect you from new threats.
In addition to faster, more thorough scans, specialized antivirus software often comes with extra tools like password managers, secure cloud storage, dedicated malware and ransomware protection, and secure online banking.
You don't have to open your wallet (or PayPal account) to benefit from these bonus features, either – all the main security software developers offer free versions of their antivirus tools that are almost as comprehensive as their premium editions.
We've used the findings of expert virus lab AV-TEST to evaluate the true effectiveness of their virus protection, but that's only half the story. Your free antivirus has to be running all the time, and if it annoys you with pop-up notifications or hits your system resources too hard you'll soon become frustrated.
With that in mind, here's our pick of this year's best free antivirus software.
1. Avira Free Antivirus
Fast, smart, effective, and well designed – Avira is the best free antivirus for Windows
Avira Free Antivirus took the top spot on our previous free antivirus roundup, and here it is again.
Yes, AV-TEST's results show it to have a micron less protection than the likes of AVG, but it's the slickest, cleanest and least system intensive antivirus package going. It's almost as if the programmers sat down to determine exactly what users would want out of an antivirus package and somehow stumbled on the correct answer: something that isn't in your face every two seconds and doesn't slow your PC to a halt just by existing.
So hooray for Avira. It doesn't even install a host of other packages (including a secure browser, VPN and safesearch plugin) by default, although they're there if you want them.
It's not the glossiest package, and the install process is a bit pre-emptive, with Windows 10 repeatedly shouting at us to update Avira before it had even finished making its way onto our test machine, but we're inclined to blame Microsoft for the latter glitch. Overall, Avira Free Antivirus is brilliant, and is our pick for this year's best free antivirus software.
Download here: Avira Free Antivirus
2. AVG AntiVirus Free
Superb free antivirus with a super-clear interface, AVG is a great choice for your whole family
Even though AVG Antivirus Free's virus protection is wrapped in AVG Zen – essentially a large advert designed to encourage you to install all of AVG's products on all the PCs in your home – we won't hesitate to recommend it.
AV-TEST gave AVG AntiVirus a 100% rating for its protection against zero-day attacks during its May-June 2016 testing, for a start. It's reasonably quick to scan after the first initial pass, and the interface – ignoring the Zen bit of it – is super-clear and easy to use. Combine it with the mobile app and you can set it to scan and disinfect a machine without having to be close to it, which is a feature you won't know you need until it's too late.
There are a few downsides. We're not super-fond, for example, of the level of permissions that AVG's Web TuneUp extension asks for – everything from 'read and change all your data on the websites you visit' to forcing your start page to AVG's own Yahoo-powered search engine – but that's an optional component.
Download here: AVG Antivirus Free
3. Panda Free Antivirus
Free antivirus that uses the power of the cloud to take the load off your computer
Although Panda Free Antivirus claims to be the world's lightest antivirus – offloading much of the processing work that would normally be done by your PC to the cloud – we found it to be slightly slower than Avira in our tests, and AV-TEST agreed. It's also right on the industry average in terms of virus detection, sitting at around the 98% mark for zero-day attacks and a hair under 100% for established threats.
Those are good numbers, and Panda is good free antivirus software – providing you remember to deny it permission to hijack your browser's home page and search facility upon installing.
Its process monitor is very useful, it scans quite quickly, and it's simple enough in its presentation for even the most technophobic user to find their way around. Switch on its automatic USB vaccination to ensure you won't get a nasty infection when you insert something you shouldn't into one of your ports.
4. Comodo Free Antivirus
Serious free security software for Windows, Comodo Free Antivirus pulls no punches
This is among the hardest-nosed free antivirus packages out there, built as it is from Comodo's serious systems administration background. Comodo Free Antivirus features a 'default deny' mode, which essentially blocks every single program that's not on its whitelist – if you let something through and your machine becomes infected, it's going to be your fault.
There's cloud scanning, so it theoretically keeps up with the latest found threats and automatically updates all users based on the newest discoveries, and indeed Comodo scored a perfect 100% against AV-TEST's barrage of zero-day threats, but its historical protection lags behind somewhat at just over 97%.
While Comodo's free antivirus software has a sharp design all its own, we'd also say it's something of a mess, unleashing window upon window on your machine and not really shutting up.
You certainly know when you have it installed. At least it includes a game mode, automatically dialling back on its actions when you need maximum performance from your machine.
Download here: Comodo Free Antivirus
5. Avast Free Antivirus
A solid free antivirus suite, albeit one with a slightly tarnished record
Avast recently bought fellow antivirus company AVG, but the newly combined company has confirmed that it will keep both brands running, so there's no need to worry about committing to either security suite.
That said, Avast Free Antivirus does concern us a little. Earlier in 2016 the Chromium-based browser it includes by default (Avast SafeZone) was found to have a serious security vulnerability not present in Chromium, so the supposed 'World's Most Secure Browser®' turned out to not be so hot. Avast patched the vulnerability immediately following its discovery, but that's poor form.
Its actual antivirus portion isn't awful. It's cleanly presented and performed reasonably well under the stress of AV-TEST's heavy punishment, and even includes a built-in LastPass-esque password manager, which is a great extra feature.
While it's heavier on the system than some, it didn't make our test machine noticeably more sluggish. Even that browser, if you trust it, is absolutely fine. But do you?
Download here: Avast Free Antivirus
6. ZoneAlarm Free Antivirus + Firewall
Robust virus and malware protection from the godfather of firewalls
Back in the dark past, when computers were beige and the internet was young, ZoneAlarm was the leading free firewall. It's therefore no surprise that ZoneAlarm Free Antivirus includes a firewall by default – a rare feature among its ilk. It's a big plus, at least if you're not competent in using Windows' own firewall; it's easy to configure and offers interesting insights into the traffic coming to and from your PC. You might even find the things it deflects quite worrying.
Unfortunately AV-TEST hasn't performed an evaluation of ZoneAlarm's antivirus portion – seamlessly integrated with that firewall – for over a year, meaning we can't offer any great confidence in it, though the June 2015 assessment did at least paint it in a flattering light.
The antivirus signatures are being maintained and the software still updated, though, so don't discount it – if you feel the need for a tried and tested firewall alongside your virus protection, this is a competent choice.
Download here: ZoneAlarm Free Antivirus + Firewall
7. Immunet AntiVirus
A cloud-based security supplement to install alongside your free antivirus software
Here's something of an odd one; Immunet AntiVirus is a tiny cloud-based free security app that's designed to run either independently or alongside your existing antivirus software. The former option isn't, perhaps, the best one; AV-TEST offers no indication as to its effectiveness, and Immunet's reputation – while strengthening in recent years – isn't that of an AV marvel.
That said, as an accompaniment to a known strong solution, we can see no reason not to at least give Immunet a shot. It's all based on collective immunity, meaning the more people use it and report back with threats, the stronger its protection becomes. Like a vaccine for your PC.
There was no noticeable slowdown on our test machine when running it alongside Avira, although in real terms it's going to hammer your CPU a little when scanning. It's also, if such a thing matters to you, almost comically ugly.
Download here: Immunet AntiVirus
8. 360 Total Security
A beefed-up antivirus suite with multiple scanning engines to pick up threats
Rolling in on a huge wave of bombast – over 52 billion threats thwarted in 2014! – comes Qihoo's 360 Total Security, which we presume is mainly getting its figures from the third-party engines it uses to scan your PC. Both Bitdefender (the default) and Avira (which should be the default) are on board, and Qihoo provides a couple of its own engines on top.
Predictably this results in a free antivirus package that eats more system resources than the rest here, which scans quite slowly, but which passes AV-TEST's 0-day and widespread virus tests with flying colours.
Download here: 360 Total Security
9. Bitdefender Antivirus Free Edition
Bitdefender's virus database is excellent, but its scanning tech is no longer cutting edge
While it comes with a strong brand behind it, Bitdefender Antivirus Free Edition strikes us as something of an afterthought these days – you have to look hard to find it, and the company's own site still crows about its compatibility with the brand-new Windows 8. Indeed, the core software hasn't been updated since 2013, though its virus definitions are at least kept up to speed.
To its credit, Bitdefender Antivirus Free Edition is at least unobtrusive, tucking itself away in the system tray by default and bringing up minimal popups. It's not the fastest, however, and we don't have total faith in its ability to spot every single virus or modern threat.
It's also worth looking at , a tiny app that's worth keeping on a USB stick. If you're foolish enough to run a machine without AV, it'll at least warn you quickly if there's something untoward on board.
Download here: Bitdefender Antivirus Free Edition
10. Windows Defender
Windows' built-in antivirus is light on features, but quiet and unobtrusive
Every new Windows installation includes Defender by default – if yours doesn't have it, grab Microsoft Security Essentials – so why bother installing third-party free antivirus protection? A glance at AV-TEST's results regarding Windows Defender's efficacy at defending against the newest zero-day threats tells the story: the May test on its Windows 8 incarnation showed that it caught just 92.1% of nasties. That's just not high enough considering its claims of cloud-based protection, however strong it may be against widespread threats.
To its credit, Defender gets on with the job and stays out of the way, protecting new installations handily. And when it comes time to install something serious, Defender ducks out gracefully – you don't need to uninstall or disable it, it just… goes.
It's simple, with the clearest interface of any package here, but it's also simplistic. So while we appreciate Microsoft's efforts to secure its operating system directly, there's a reason there's still a third-party antivirus market.
Download here: Windows Defender