Free protection from online threats
Whenever your PC is connected to the internet, your data and privacy are at risk. Malicious file downloads are still the most common way for viruses, trojans and malware to sneak in, but unpatched security vulnerabilities in your operating system and other software can also leave you exposed.
There's a wealth of free antivirus software to protect you from such disasters, but not all free antivirus packages are created equal. We've rounded the best free downloads to keep you safe online, looking at their effectiveness, speed and ease of use. Have we missed your favourite? Let us know in the comments below.
1. Avira Free Antivirus
Fast, friendly and effective, with added online tracking protection
Fancy benefiting from the experience of 477 million people? That's the number of times Avira Free Antivirus has been installed, and its cloud-based security pools their history of virus exposure: if a user on the other side of the planet encounters a new nasty, all of Avira's users get the ability to detect it.
It's fast, friendly, doesn't give you too many prompts and alerts, can identify unwanted apps inside legitimate applications and most importantly of all, achieved 100 per cent malware detection in tests - a score shared with BitDefender and Kaspersky, but significantly ahead of many of its rivals.
This impressive set of functions makes Avira Free Antivirus our top-rated free security program. Read on to discover eight more of the best free antivirus tools available right now. Have we missed your favorite? Let us know in the comments below.
2. Bitdefender Antivirus Free Edition
One of the best free antivirus tools around, offering fast, discreet protection
Some antivirus programs want to know all about you and pop up excitedly to tell you about new updates or every potential threat they've stopped. Not BitDefender Antivirus Free Edition. It's the ninja of antivirus software, lurking silently until it needs to unleash its skills.
It's ad-free and nag-free, maintenance-free and lightweight in operation: it doesn't slow down your PC or interrupt your working day for no good reason.
If you like to fiddle then you might find other apps more to your liking, but for those of us who prefer a little peace and quiet BitDefender is hard to beat.
3. AVG AntiVirus Free 2016
Feature-packed, with a user-friendly interface and remote-activated scans
We've been using AVG AntiVirus Free for years, and it's a very good antivirus program - albeit a little too keen to inform us about things we don't really need to know.
The dashboard is user-friendly, the scanner checks links as well as downloaded files, and there's a clever tool that enables you to scan your PC from your mobile phone if you think it's become infected.
The paid-for versions attempt to lure you with promises even more robust download protection, data encryption and firewalls to make online threats redundant, but the standard free edition of AVG offers a great deal of protection for no money.
4. Avast Free Anti-Virus 2016
Malware and virus protection, with added security for your home network
Avast Free Anti-Virus 2016 is an impressive offering. It protects against malware and viruses, can identify weaknesses in your home Wi-Fi and includes a well-implemented password manager to keep your complex login details safe and easy to access.
As with most free products you get even more features if you're willing to pay - there's no anti-phishing protection or spam filtering in Avast Free - but it's nonetheless perfectly respectable and keeps you safe from the most common online attacks.
5. Ad-Aware Free Antivirus+
A comprehensive online security toolkit that covers all the essentials
As the name suggests, Ad-Aware Free Antivirus+ started life as an anti-adware program, and it was a very good one. Over the years it's evolved to address more threats, so today it's a fully-fledged security suite that scans downloaded files, keeps an eye out for spyware, enables you to compare web addresses against known offenders and won't interrupt you when you're playing a game.
It doesn't have the features of its paid-for siblings - if you want anti-phishing email protection, parental controls and file destruction you'll need to pay for it - but the core product covers the essentials very well.
6. 360 Total Security 2016
Combines four antivirus tools in one, but not the fastest package around
Why take one virus detection engine onto the internet when you can take four? 360 Total Security 2016 from Qihoo combines Avira, BitDefender, 360 Cloud Scan Engine and 360 QVMII AI Engine, so in theory it should probably detect threats before they've even been invented, let alone released.
But can you trust it? In some circles Qihoo is seen as the Volkswagen of security software, tweaking its programs to gain artificially inflated scores in tests - and the BitDefender engine is switched by default, so you aren't getting quite the protection you might think until you adjust some settings.
It's powerful if a little slow, but lingering trust issues aren't great when you're deciding which firm can keep your stuff safe.
7. Panda 2016 Free Antivirus
Antivirus that uses cloud processing power to take the weight off your PC
Panda Free Antivirus has headed for the clouds with this version, which does all the heavy lifting on Panda's servers to reduce the load on your PC.
As we've come to expect from free programs there are lots of optional features that you only get if you pay - Wi-Fi scanning, password management, file encryption and parental controls - but the basics are covered well and Panda scores well in independent virus detection tests.
It isn't quite up there with Avast, AVG or BitDefender, but it's still very good.
8. Microsoft Security Essentials and Windows Defender
Microsoft's tools are easy to use, but not as effective as third-party software
Who better to protect your PC than the company whose operating system facilitated all the security issues in the first place? We kid, of course - Windows is more secure than it's ever been, and Microsoft has invested massive sums in system protection in the form of Microsoft Security Essentials for Windows 7 and Vista, and Windows Defender, which is built into Windows 8 and 10.
The result, as you'd expect, integrates very well with Windows, but it consistently lagged behind the likes of BitDefender in independent testing. While the 2015 version was pretty hopeless in detection tests, the 2016 one is a vast improvement - but Microsoft is still on the back foot and rival programs offer better protection. It's much, much better than nothing, but it's not the best.
9. Your bank
Find out what services your bank offers to keep online transactions secure
To keep your account details safe online, many banks offer free licences for antivirus software you'd normally expect to pay for.
McAfee subscriptions are free to MBNA card and HSBC bank customers, saving you £40 (about US$57, AU$79), while users of Barclays online banking can get a free 12-month subscription to Kaspersky Internet Security worth £30 (about US$43, AU$59).
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