Introduction
Antivirus software remains essential in 2023, especially when it comes to protecting against real-time threats, often delivered via the web in the form of ‘drive-by downloads’.
We’ll see if Microsoft Defender, built into Windows, is your best choice for protection, and take a look at the best free antivirus choices for older operating systems, for users who need extra tools, and for those who don’t want the simplest AV around.
Alternatively, if you’re happy to pay a monthly subscription fee in order to get access to more features then you can check out our list of Best Antivirus instead. But if you’re not prepared to pay a dime, then these are the best free antivirus tools you can install right now.
How we test
For raw performance against malicious software, we use data from multiple testing houses: AV-Test, SE Labs and AV-Comparatives. Of these tests, we prioritise ‘real-world’ performance, in which antivirus detection engines are exposed to live threats.
We also draw on system performance data captured by AV-Test and we inventory and compare features on an application-by-application basis, highlighting both useful tools and unexpected sticking points in the workflow and interfaces.
- Excellent integrated Windows 10/11 interface
- Excellent malware protection
- No need to install anything
- Free
- System impact isn’t as low as you might expect
- Works on Windows 7 & 8.1
- Very accurate
- Ransomware defence
- More false positives than some rivals
- Works on Windows 7 & 8.1
- Super-accurate
- Ransomware defence
- No more effective than Microsoft Defender
- Heavier on system resources than Avast or Microsoft Defender
- Works on Windows 7 & 8.1
- Includes lots of extra tools
- Effective malware defence
- Ransomware defence isn’t included
- No silent mode
- Works on Windows 7 & 8.1
- Extremely simple to use
- Less effective than some rivals
- No ransomware defence or scheduled scans
Microsoft Defender Antivirus
Best overall free antivirus
Pros
- Excellent integrated Windows 10/11 interface
- Excellent malware protection
- No need to install anything
- Free
Cons
- System impact isn’t as low as you might expect
Built into Windows 10 and 11, Microsoft Defender is the most consistently reliable antivirus suite around. It got perfect 100% protection scores in AV-Test’s most recent tests, 99.7% in AV Comparatives’ latest real-world test and 98% in SE Labs’ late-2021 tests. That’s top-flight performance, and even though it didn’t get the best scores in all those tests, it regularly does spot 100% of malware in tests and is easily on a par with any third-party antivirus solution around.
Core anti-malware components include real-time protection and on-demand scans covering everything from quickly checking a folder to a comprehensive offline scan that checks for hard-to-remove threats such as rootkits by scanning the system without booting into Windows. However, scheduled scans have to be set up via Windows Task Scheduler.
As well as virus protection, Defender includes Windows Firewall, parental controls and remote management of your family’s devices, reputation-based site blocking in Edge and application blocking in general, system health reports, and the ability to disable all notifications.
Although Microsoft Defender is incredibly good, you’ll need an alternative such as Avast or Bitdefender ’s free antivirus if you’re running an older version of Windows.
Reviewer:
K.G. Orphanid
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Full review:
Microsoft Defender Antivi
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us review
Avast One Essential
Best antivirus for older PCs
Pros
- Works on Windows 7 & 8.1
- Very accurate
- Ransomware defence
Cons
- More false positives than some rivals
Partly supported by advertising and partner promotion, Avast Free Antivirus includes core protection modules against malware via web, file, network and mail, as well as ransomware defence for your choice of critical folders.
It carries out real-time scanning of potential threats, as well as on-demand and scheduled system scans, and has a built-in do not disturb mode that’s automatically activated whenever you run a fullscreen application.
Avast’s malware detection engine got perfect scores in AV-Test’s latest real-world exposure and reference file scanning tests, with a six-out-of-six system performance racing and only two false positives. It blocked 99.7% of malicious content in AV-Comparatives’ real-world protection tests, with just one false positive, and achieved a respectable 97% accuracy rating in by SE Labs’ late-2021 tests.
It’s no more accurate than Microsoft Defender , so Windows 10 and 11 users should stick to that, but is a solid choice for older Windows PCs.
Reviewer:
K.G. Orphanides
Full review:
Avast Free Antivirus
Bitdefender Antivirus Free Edition
Best interface
Pros
- Works on Windows 7 & 8.1
- Extremely simple to use
Cons
- Less effective than some rivals
- No ransomware defence or scheduled scans
Bitdefender Antivirus Free Edition shares its detection engine with the company’s paid-for editions, but provides an otherwise bare-bones experience.
Bitdefender’s engine typically performs well in tests. It achieved a 100% detection rating in AV-Test’s real-world and reference scanning tests, with only a single false positive and a 99.7% rating with three false positives in AV-Comparatives’ most recent real-world protection test. The software was not included in SE Labs’ recent tests.
Unlike most of its free antivirus rivals, you have to create a Bitdefender account and register Antivirus Free to activate the software. A free account covers up to three Windows PCs, which includes access to a Bitdefender Central web portal, a helpful remote device management features, such as the ability to check the protection status of each system and see any threats that might have been detected on them.
You get real-time and on-demand scanning, and features like optional (but on-by-default) automatic scanning of media when you insert a disk or drive. However, you can’t schedule scans and there’s no dedicated ransomware defence module.
It can’t quite match Microsoft Defender ’s outstanding performance if you’re running Windows 10 or 11 systems. However, it’s a good choice if you’re still using Windows 7 or 8.1, although I miss the streamlined interface of its previous incarnation.
Reviewer:
K.G. Orphanides
Full review:
Bitdefender Antivirus Free Edition
AVG Free Antivirus
A good alternative to Microsoft Defender
Pros
- Works on Windows 7 & 8.1
- Super-accurate
- Ransomware defence
Cons
- No more effective than Microsoft Defender
- Heavier on system resources than Avast or Microsoft Defender
Bought by rival Avast in 2016, AVG’s anti-malware suites use the same detection engine as its stablemate, but with a different interface and a slightly different range of integrated tools.
AVG Free Antivirus has a more limited feature set than its paid-for counterparts, but the essential real-time and file-scanning anti-malware components are there, along with on-demand and scheduled scans, browser and email scanning components, and an anti-ransomware tool that blocks unauthorised programs from making changes to selected directories.
AVG’s detection engine performed almost identically to Avast’s in recent tests by AV-Test, AV-Comparatives and SE Labs. AVG detected and protected against 100% of malware in AV-Test’s real-world and flat file exposure tests, 99% of malware in SE Labs’s tests, and 99.4% of malware in tests by AV-Comparatives. However, AV-Test’s data shows that AVG has a greater impact on performance.
AVG is a long-standing public favourite among free anti-malware tools and continues to do the job reasonably efficiently. However, it’s no more effective than Microsoft Defender , which comes pre-installed on Windows 10.
Reviewer:
K.G. Orphanides
Full review:
AVG Free Antivirus
Avira Free Security
A mediocre antivirus with lots of features
Pros
- Works on Windows 7 & 8.1
- Includes lots of extra tools
- Effective malware defence
Cons
- Ransomware defence isn’t included
- No silent mode
Avira has a longstanding reputation as a lightweight antivirus suite that’ll run on almost anything. Unfortunately, its performance in the most recent tests by AV-Test and AV-Comparatives wasn’t quite up to most of its rivals. Avira Free Security didn’t put in a particularly good performance in AV-Test’s real-world tests, scoring 99% one month and 100% the next.
It protected the test system in 100% of AV-Comparatives’ test exposures though. However, the most damning result same from SE Labs’ late-2021 tests, where it got a protection rating of 93%, as it was compromised by three of 100 threats, and had to neutralize one after infection. It’s by no means ineffective against the latest malware, but most of its rivals are just a bit better.
Free users only get access to the Real-time protection module, plus scheduled and on-demand scans. If you want the dedicated web, email and ransomware protection modules, you’ll be prompted to subscribe to Avira Prime. Similarly, the free version has no do-not-disturb mode for gaming.
It comes with plenty of other tools for system optimisation, file shredding, and tweaking Windows’ privacy settings, plus a very limited 500MB/month VPN allowance. These are all handy, but can’t quite outshine Microsoft Defender for Windows 10 and 11 users.
Reviewer:
K.G. Orphanides
Full review:
Avira Free Security
FAQs
Yes, all of the antivirus options listed are safe to use.
Both forms of antivirus can detect and block malware, but paid-for options can unlock additional features such as VPNs and advanced parental controls.
Every antivirus listed is free for an unlimited time. But you will need to pay for the premium tier if you want to unlock additional features.
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Editorial independence
Editorial independence means being able to give an unbiased verdict about a product or company, with the avoidance of conflicts of interest. To ensure this is possible, every member of the editorial staff follows a clear code of conduct.
Professional conduct
We also expect our journalists to follow clear ethical standards in their work. Our staff members must strive for honesty and accuracy in everything they do. We follow the IPSO Editors’ code of practice to underpin these standards.
Editorial independence
Editorial independence means being able to give an unbiased verdict about a product or company, with the avoidance of conflicts of interest. To ensure this is possible, every member of the editorial staff follows a clear code of conduct.
Professional conduct
We also expect our journalists to follow clear ethical standards in their work. Our staff members must strive for honesty and accuracy in everything they do. We follow the IPSO Editors’ code of practice to underpin these standards.