Malware is any form of malicious software – not just viruses, worms and keyloggers, but also nuisance programs like adware that add toolbars to your web browser, bombard you with popup windows, hijack your homepage, and send your personal data to advertisers.
A good antivirus suite is an excellent first line of defence for your PC, but it's often a good idea to install additional anti-malware software to boost your protection from a more diverse range of threats. Alternatively, you could replace your existing security software with a whole new suite designed to protect against all kinds of malware.
Here we've rounded up the best free anti-malware software for Windows – whether you're looking for a whole new security package, or just an additional program to give your regular antivirus a boost.
1. BitDefender Antivirus Free Edition
Discreet but effective, BitDefender is the best free anti-malware for your PC
BitDefender Antivirus Free Edition is the strong, silent type. This anti-malware software doesn't even ask questions when you install it – it just quietly gets on with the job of identifying and eliminating anything that poses a risk to your safety and security.
It has B-Have, which looks for apps behaving badly; link scanning to identify cons; proactive malware and spyware scanning that can detect threats nobody has encountered before; and boot scanning every time you start your PC.
Ad-free, nag-free and hassle-free, BitDefender Antivirus Free Edition is a great product that runs quickly and silently while you get on with something more interesting.
Its comprehensive suite of tools to protect your PC makes BitDefender the best free anti-malware software you can download today. It's all the protection you need in one handy package.
Review and where to download: BitDefender Antivirus Free Edition
2. Panda Free Antivirus
Cloud-based protection from malware that takes the pressure off your processor
We're big fans of Panda's security products, and Panda Free Antivirus is smarter than ever before. It's cloud-based, with all the heavy processing happening on Panda's servers, so the load on your PC is lessened considerably (though there is still a reduction in performance).
There are premium anti-malware products that offer more features – Wi-Fi scanning, password management, encryption, parental controls and so on – but Panda Free Antivirus offers excellent real-time protection and is ridiculously simple to use.
If your PC is a little underpowered, Panda could be the anti-malware tool for you.
Review and where to download: Panda Free Antivirus
3. AVG AntiVirus Free
A simple interface and effective scanning with remote activation
If you're looking for anti-malware software that keeps quiet and won't disturb your work, be warned - AVG Antivirus Free is quite vocal with its notifications, and irks us from time to time with pop-ups telling us we've done something fantastic with regard to our online safety.
As an anti-malware app, though, it's very good. The dashboard is user-friendly, there's protection not just from downloadable threats, but from dodgy links too, and you can use your mobile to scan your PC remotely, which is pretty clever.
The paid-for Pro model has more security options - it has more robust download protection, offers data encryption includes a firewall - but the free version offers decent protection for most PC users.
4. Ad-Aware Free Anti-Virus+
All the anti-malware essentials you need, but lacking phishing protection
Like many security software firms, Lavasoft offers its Ad-Aware Free Anti-Virus+ as a free tool in the hope you'll upgrade to its paid-for products. It therefore doesn't have some of the more advanced anti-malware and anti-spyware features you'd pay money for, such as phishing protection, parental controls and a digital file shredder.
What it does have, however, more than covers the essentials: it scans downloads, checks for spyware, offers safe browsing via a list of known malicious websites and has a game mode so security notifications don't interrupt your frag-fests. Not bad for no money.
5. MalwareBytes Anti-Malware
An excellent anti-malware tool, but the free version lacks real-time protection
You can use MalwareBytes Anti-Malware free for as long as you like, but there's an important caveat: real-time protection, the fast 'hyper scan' mode and malicious website blocking features all expire after 14 days - and that means you're missing out on some of the program's best features.
MalwareBytes has a deserved reputation for destroying malware and spyware that other programs miss, and its chameleon technology - which once again expires after a fortnight in the free version - means it's less susceptible to attacks that deliberately target security software.
Review and where to download: Malwarebytes Anti-Malware
6. SpyBot Search and Destroy
An anti-malware and anti-spyware stalwart that's ideal for diagnosing existing infections
SpyBot Search and Destroy is a veteran of the malware wars, dating back to the first adware in 2000, and while it doesn't scan for viruses – that's in the Home version, which is $13.99 (about £10, AU$20) – the free version does a decent job of finding and fixing adware, malware and spyware.
It's more of a system repair tool than a system protection tool, however, and you need to be careful where you get it from: there are fake versions in circulation designed to cause damage, not fix it. The version linked here is the real deal.
7. Avast Free Antivirus
Reliable package anti-malware with built-in password management
Avast is another old-timer, and has been protecting Windows from malware and spyware since PCs were made of wood. Avast Free Antivirus is the lightest, fastest version the company has ever shipped (the bad old days of security software slowing your PC to a crawl are thankfully long gone) and it supplements the anti-malware protection with a nifty password manager and home network monitoring, which can identify weak points in your Wi-Fi.
As with most free products, not all the goodies are available for nothing, so for example if you want anti-phishing protection or spam filtering you'll need the paid-for version, but the free edition is still a very comprehensive security package.
8. Emsisoft Emergency Kit
A lifesaver if your PC has already been infected with malware, but not a preventative tool
Most security software tries to stop malware and spyware getting onto your system. Emsisoft Emergency Kit doesn't: it's the 911 call of security software, the app you use when your PC's been poked by something unpleasant.
It's designed to be portable – an anti-malware app you carry around with you on a USB stick – and its system requirements are tiny: just 200MB of RAM, so it'll run happily on any PC with 1GB memory or more. With two million malware signatures, Emsisoft Emergency Kit can restore almost any infected PC to rude health.
For experts only – get detailed reports on a misbehaving PC so you can diagnose the problem
Originally developed by Trend Micro and now available via SourceForge, HijackThis isn't anti-malware software for the faint of heart or tech-phobic: it generates an exceptionally detailed report on your system, enabling you to spot potential problems and malicious software.
It's very fast and very thorough, but it's about recognizing malware behavior rather than specific products. It tells you what's going on, and it's your job to interpret it and take action. In the wrong hands, that power could be disastrous. This is one for experienced users only.
10. SUPERAntiSpyware Free Edition
An outdated interface belies a solid manual malware scanner with plenty of options for protecting your PC
Not just anti-spyware – SUPER anti-spyware. Does it live up to the name? Yes and no. SUPERAntiSpyware Free Edition lacks real-time protection and scheduled scanning, so it's a tool you need to remember to run manually, and the interface appears to have been designed in the dark by maniacs.
The core anti-malware software is solid though, with lots of scanning options for picking up malware and spyware, registry repair, behavioral scanning and daily threat updates. Perhaps not super, but pretty good.