There is no excuse for not having antivirus software on your PC because there are lots of free packages. And the good thing about having a free product from one of the leading companies is that they use the same 'engine' as their paid-for products.
Your buying guide for antivirus software
You do get more if you buy an internet security suite, but what you get in the free version is stripped down package with a smaller feature set. Don't expect to get extras such as spam filtering, improved firewalls, parental controls, password managers and support for mobile devices, although some of this can be had for free.
The free offerings from Avast, AVG, Avira, Bitdefender and Panda all offer basic antivirus and anti-malware protection, giving you a good chance to keep your PC free of threats which could lose you data and take a lot of time to put right.
Since testing antivirus software with real malware requires a lot of time and effort, not to mention extremely specialist knowledge, we don't do this ourselves. Instead, we use the latest results from several well-respected independent test houses, including SE Labs, AV-test.org and AV Comparatives.
Is free antivirus really free?
Best is Bitdefender, which claims not to share information with anybody outside its own company or subsidiaries. We think this is as it should be with a security product, but second-best is the assumption not to share, with an opt-in, should you want to receive ‘relevant’ offers. This is what Avast and Avira do. Panda does the same as AVG, requiring you to specifically unsubscribe to avoid security-related emails.
Does free antivirus software work?
Antivirus software is designed to prevent damaging programs from infecting your PC and laptop. All the free products here do that, but not all are as effective as others. As a secondary task, though, the full paid-for products should reduce the amount of unwanted advertising and offers that get through to you, and they usually offer quite a few other features as we mentioned above.
But without further ago, here are reviews of the leading free AV programs – you really can get something for nothing.
Best free antivirus 2017 - Antivirus software reviews
Best free antivirus: AVG
AV-Test’s results from testing in July-August showed that its protection was above the industry average and awarded it 5.5 out of 6. It achieved the same for performance, so won’t slow your computer down. Again, it was given the same high score for usability, and as we’ve used AVG Free on our own PC for the past year, we can – anecdotally – agree that it runs transparently in the background and you don’t really notice it. And that’s exactly what you want from your antivirus.
AVG has a simple-to-understand dashboard so, if you do ever venture to it, it’s very clear whether it’s up to date and protecting your PC.
In addition to an AV engine, it also warns you of unsafe web links and can block unsafe email attachments.
Best free antivirus: Avast
Unlike some firms, Avast doesn’t hide its free antivirus offering so you can’t find it. A big orange button on its homepage makes this version more obvious than its paid offerings, so it’s a good start.
As well as basic antivirus protection, it offers protection from unknown threats and a handy password manager so you can log into sites in your browser by remembering just one password.
You don’t get the browser extension that warns of fake sites (such as banks), nor a privacy shield or spam filtering. Those come with Avast’s Internet Security package, while Premier adds automatic software updating and a file shredder.
The good news is that Avast’s antivirus protection is very good. SE Labs currently rates it at 92 percent overall, down two points from the July-September 2016 tests. AV Comparatives found that it blocked 99.7 percent of threats in its September 2016 tests. It also found that Avast had the least impact on your PC’s performance – thanks in part to the fact that Avast runs a “significant proportion” of its analysis in the cloud.
AV-Test rates protection, performance and usability, giving Avast 6.0, 3.5 and 6.0 out of 6 respectively from it's November-December 2016 tests.
Avast asks you to opt-in to receive relevant offers, which may persuade some over AVG's forced opt-in to sharing data. Overall, then Avast is one of the best free antivirus packages around.
Best free antivirus: Avira
Avira has previously topped our list of the best free antivirus programs, and it’s still a very strong contender. We like that you can download the full program as well as just the 4MB launcher, giving you the option to start the installation and then leave it to download the rest. It’s not alone in this, but it’s the only one we know of which also lets you download the full thing.
The interface is well designed and easy to use, and the latest version includes a couple of new features in its SearchFree Toolbar: a website safety advisor and the option to block advertising companies from tracking you online.
At first sight, it appears Avira bundles a firewall with its product, but this turns out to be an integrated front-end to the Windows firewall.
File scans can be scheduled and by default there’s a quick scan set to repeat every 168 hours or, as we techies call it, weekly. We reckon a quick scan could run more frequently than this, though.
A year ago, AV-Test gave Avira perfect scores, and this year it still did commendably well. In its recent tests in November and December, it handed a 6.0 for protection and 5.5 out of 6 for performance and usability.
SE Labs didn’t test Avira in its recent roundup, but AV Comparatives gave Avira full marks for blocking 100 percent of threats.
Ultimately, Avira does an excellent job – even when compared to paid-for Internet Security programs.
Best free antivirus: Bitdefender
Bitdefender’s paid-for Total Security package is excellent, and it’s no surprise to see its free offering score well: it uses the same virus detection engine.
In fact, AV Comparatives awarded it the unbeatable score of 100 percent, successfully blocking all malware during its tests in September. There were no false-positives, either, which is when safe files or programs are reported as being unsafe.
AV-Test also praised Bitdefender, giving it full marks for protection and usability. It slipped by half a point in performance in the November and December 2016 tests simply for being very slightly behind the industry average.
SE Labs’ tests (from July-September 2016) found it wasn’t infallible at that time, with it being compromised by a number of threats and awarding it a protection rating of 73 percent.
Overall, Bitdefender is easy to use, is lightweight and – in general – offers good protection for your PCs. You can read our full Bitdefender Total Security 2017 review for more details.
Best free antivirus: Microsoft
Windows Defender is built into Windows 10 and Windows 8, so it’s arguably the easiest option for most people since it’s probably in operation already unless you’ve disabled it or installed another antivirus program.
Unlike in the past, when it merely paid lip-service to virus protection, the modern Security Essentials is a credible and reliable AV engine. OK, it’s not the very best out there, but it certainly does the job.
If your PC or laptop is running Windows 7, you can download Microsoft Security Essentials for free.
As the name suggests, it offers basic antivirus protection. The only difference between MSE and Windows Defender is that the latter offers better protection against rootkits and Bootkits.
SE Labs awarded MSE 88 percent overall in its October-December 2016 tests, down from 91 percent in the preceeding three months. It is therefore currently behind AVG Free (93 percent) and Avast (92 percent).
AV-Test gave it 4.5 out of 6 for protection. AV Comparatives found it blocked 96.2 percent of threats, which is below all the other packages here, but as ever, these results all change on a monthly basis.
There are better choices than Security Essentials, but if you’re running Windows 8 or 10 with Defender built in, all you need to do is check that it’s enabled.