Best Free Antivirus 2018: 6 best free AV packages to keep your PC safe

Best Free Antivirus: We look at the four best free anti-malware solutions on the market right now, updated with the latest results in September 2017.

Antivirus might not be as vitally important to your online safety as fear-mongering security firms might have you believe, but for those who want to surf the web worry-free, it’s always a good idea. And with so many decent free options available, the choices have never been wider. Here, we look at Windows 10’s built-in Defender and three of the best alternatives.

While paid-for antivirus software is beyond the scope of this group test, we hope to provide you with the information you’ll need to make an informed assessment about whether a pre-installed commercial package – such as those often bundled with new laptops – will be more, or less, effective than its free competitors.

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Detection engines

The key part of any antivirus software is its detection engine. Such engines use a vast library of data on known threats and compare it to the files on your computer and web pages to see if they look like, or behave like, threats. Detection engines are at the core of most antivirus companies’ business, and you’ll generally find that a company’s free product uses the same engine as its paid-for version, although the latter may be equipped with additional features, such as firewalls and system optimisation tools.

Modern antivirus software constantly monitors your PC and scans software, files and websites in real-time to detect potential threats, but you can still run manual and scheduled scans for extra peace of mind. By default, most AV programs run an optimised scan that checks the files most likely to have been compromised. By comparison, running a more thorough scan will take longer; our reviews list the amount of time a full scan takes to run on a freshly installed Windows 7 system with two 2.1GHz cores and 8GB of RAM.

Data sources and how we test

We use the following data sources and tests to come up with our scores:

•    AV-TEST: A well-respected organisation that tests every major AV firm to their absolute limits. AV-TEST produces results based on protection, false positives and system performance impact.
•    SE Labs: A UK-based antivirus testing firm that uses up-to-date threats found on the web at the time of testing. The company also tests for false positives.
•    Our own test system: We test how much of an impact each AV company’s system scans have on our test system; this is important if you have an old PC.
•    Features: In a world where all AV companies have something extra to offer, we look at which firm is bundling the best extra features, as well as those that are trying to sneak money-making programs into your installations

The test data we’ve used was collected between May and June 2017, using the most up-to-date versions of the antivirus software available. AV-TEST carries out both real-world testing, in which systems are exposed to live contaminated websites and emails, and reference set tests, in which several thousand malicious files collected in the previous four weeks are introduced to the system.

The pitfalls of ‘free’

While you don’t have to hand over any cash to download free antivirus software, its makers need to fund their business somehow. Some products, such as Avira, show unobtrusive adverts, while others are paid to bundle software and services from other companies with their product’s installer or web browser plugins.

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Any product that’s available in paid-for, as well as free, versions, will encourage you to upgrade with varying degrees of persistence, with some including buttons for features that are only active for paid users in their main interface. Many free AV providers encourage users to register for free accounts by providing online monitoring tools that you can use to manage and secure other devices associated with the same account, such as phones and tablets.

Our reviews detail any obtrusive advertising or promotional features in each free AV suite and, where possible, tell you how to avoid them.

Antivirus software also by default reports back to its manufacturer when it encounters unknown malicious and even benign files. This data gathering is an important function of free antivirus suites as far as their creators are concerned. In practice, it means that the malware databases upon which the software relies are kept constantly up to date, helping to protect all users and making both paid-for and free versions more accurate.

Meet our expert

K.G. Orphanides: An industry veteran, K.G. has a special interest in internet security, networking, PC hardware, free and open source software, and knows more than anyone would ever really want to about cloud-based software and services. K.G. still remembers when most people still knew “the cloud” as “other people’s servers”.

Kaspersky Free

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Key features:

  • Email scanning module
  • Bootable rescue disk available as separate download
  • Windows Vista/7/8/8.1/10
  • Requires Intel Atom 1.6GHz or faster, 1GB RAM, 920MB free disk space, 64MB
  • Intel GMA950 video card or better, screen resolution of at least 1024×600

Big-brand AV software goes free-to-use

Kaspersky’s release of its new Free Antivirus has instantly made it one of the top players in free malware protection, as it uses the same detection engine as the company’s well-regarded commercial products.

Currently, the program is only available from the company’s global site, and only in US English, although regionalised versions are promised in the coming months. After installation, you’re prompted to sign into or create a My Kaspersky account – you’ll need this to use the free AV software.

You also only get a 366-day license, which will have to be renewed every year – this is a slight irritation, similar to Avast’s former free licenses. As with most free antivirus software, Kaspersky Free also suggests upgrading to a paid-for version if you want extra features. However, all but the least confident internet users should be able to correctly differentiate between Kaspersky’s free and commercial products.

The client closely resembles its paid-for counterpart in its clean look and feel, with a main screen that displays your protection status, along with options to scan your system, update its virus database and open extra tools. A number of other options are greyed out, prompting you to buy one of Kaspersky’s paid-for anti-malware suites.

While Kaspersky Free is light on features compared to its commercial counterparts, it provides a few extra features in addition to the powerful, proven antivirus engine. Browser plugins provide link-checking capabilities within search results, without redirecting your default home page or search engine.

You also get 200MB of daily data on Kaspersky’s Secure Connection VPN service – which has to be uninstalled manually if you remove Kaspersky Free Antivirus – and an on-screen keyboard can be enabled to foil keylogging malware. While you can’t burn a Kaspersky Rescue Disk from within the program, ISO images are available to download for free from the company’s website.

The core file, web, instant messaging and mail scanners are included, but extra features such as application activity monitoring, a private browsing mode, email spam filtering, ad blocking and webcam protection are only available in paid versions.

Advanced options allow you to set how paranoid the scanner is, schedule scans and configure the program’s default behaviour and what notifications you get. A full scan at default settings is markedly time-consuming, clocking in at 37 minutes even on a recent Windows 10 installation on our reference systems.

Protection and performance

Although neither of our usual sources of anti-malware test results, AV-TEST and SELabs, have yet tested this specific product, plenty of test data is available for the same detection engine, which is used in all of Kaspersky’s paid-for antivirus products. Bear in mind that these may include additional features to help protect your system, but that the detection engine is the most critical feature.

Kaspersky’s engine, in its commercial Internet Security product, is consistently among the best-performance both AV-TEST and SELabs’ tests. It scored 100% in both real-world exposure and flat file scanning tests at AV-TEST, with no false positives, and significantly less impact on system performance than the industry standard, netting it perfect scores all round.

SELabs’ latest report indicates similarly strong performance, with perfect 100% detection and protection and no false positives.

We look forward to seeing dedicated tests of the free product – which is why we’re holding off on awarding a perfect 10 to the program – but the accuracy of Kaspersky’s detection engine makes Kaspersky Free Antivirus easy to recommend for all your free antivirus needs.

Microsoft Windows Defender

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Key features:

  • Bootable Windows Defender Offline rescue disk available as separate download
  • Built into Windows 8/8.1/10
  • Available for Windows Vista/7 as Microsoft Security Essentials
  • Will run on any Windows system


New, improved and better than ever

Microsoft Windows Defender – the default free antivirus tool built into Windows 7 and above – has historically been a decidedly no-frills option when it comes to malware defence. But it actually provides a reasonable level of protection on those systems that you haven’t had time to install anything else. Low-power systems that lack the resources to run extra software in the background also benefit.

Windows Defender’s appearance and features vary depending on which version of the operating system you’re running it on. In particular, the latest Windows 10 Creators Update introduces a number of new tools and a completely revised interface for Defender.


While previous versions simply reported on Defender’s protection status, let you run scans and little else, the new Windows Defender Security Centre provides access, settings and reports for multiple modules to do with the security of your PC. The homescreen provides an overview of your protection status, including when Defender last updated itself and scanned for malware.

It also includes dedicated tabs for different features. Virus and threat protection is home to your usual quick, full and custom scans, plus a new, intensive offline scan mode in its advanced options, designed to hard-to-remove threats. You can also manually update virus definitions and enable or disable options such as cloud-based protection and real-time protection.

The device performance and health section monitors anything that might go wrong with your system over time and offers up a ‘Fresh Start’ option that reinstalls Windows while retaining your files and most of your settings. Firewall configuration and control is now easy to find in its own tab, where you open ports, configure notifications, and set different settings for private and public networks.

There’s no indication that the underlying virus databases and heuristic scanning rules used by Defender have changed relative to previous versions, so the results from AV-TEST and SE Labs in recent months can still be regarded as representative. However, with Microsoft now positioning Defender as a fully fledged security centre, we’ll be watching for potential performance improvements with interest.

App and browser control allows you to set the strictness of Microsoft’s SmartScreen utility, which can warn against or block apps that Microsoft’s remote verification service hasn’t seen before. Finally, your Family options provide device and account management for children who use Windows devices, allowing you to enable content filtering for the web, control the apps they install and the amount of time they spend in front of the screen.

Protection and performance

We now have up-to-date test results from AV-TEST and SELabs which show that, as suspected, there are no major changes to the performance of the underlying virus databases and heuristic scanning rules used by Windows Defender.

It uses the same malware detection engine as Microsoft Security Essentials for Windows 7, and SELabs’ results were obtained from that version. AV-TEST’s latest results were produced using the default Windows 10 version of Defender, with all the features we’ve mentioned here.

Both testing labs saw a dip in performance from the detection engine in real-world live malware exposure tests, compared to similar tests earlier this year, although it’s important to remember that detection rate fluctuations are common among anti-malware products.

In AV-TEST’s latest real-world tests, Defender achieved a detection rate of 99% in May and June. When it came to detecting malware in a reference set of samples, it picked up 99.8% in May and 99% in June. It threw up more false-positive warnings on legitimate software than usual, however. The same engine, in the form of Microsoft Security Essentials, scored 78% in SELabs’ live malware exposure tests, down from 84% earlier in the year, but avoided most false positives, giving it an overall score of 93%.

While Windows Defender improves on simple benchmark performance tests – compared to third party antivirus suites – when just running in the backgrouns, AV-TEST’s more involved and nuanced testse found that it can have a noiceable performance impact. This was particularly obvious when launching sites and applications, giving it a performance score of 5 out of 6. Running a full malware scan on our reference system took a somewhat extended 32 minutes and 33 seconds.

If you’re running the latest version of Windows 10, Defender has grown into a surprisingly capable set of protection tools that have a minimal impact on system performance and – of course – blend in perfectly with the look and feel of the operating system. However, its malware detection capabilities, while providing adequate defence, are no match for rival free products produced by dedicated antivirus firms, such as Kaspersky or Avira’s free offerings.

Avast Free Antivirus

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Key features:

  • Free product no longer requires registration
  • Email scanning module
  • Can create bootable rescue disk
  • Windows XP SP2/Vista/7 SP1/8/8.1/10

One of the best free AV packages available

The Avast Free Antivirus 17 product has been slimmed down and polished up compared to previous iterations. A clean, dark interface meshes nicely with the general look and feel of Windows 10’s Modern UI, but won’t look too out of place on a Windows 7 desktop, either.


A status screen shows whether you’re currently protected and lets you instantly run an optimised Smart Scan. At the top right, you can sign into your Avast account – but the company has finally dispensed with its requirement that users register for an annual free licence to use it.

We’re pleased to see this, since the registration requirement made the program rather unfriendly for inexperienced computer users, who were easily confused by the difference between a free registration and upgrading to one of Avast’s paid-for versions.

Avast still shows that its free product has only a one-month licence, although this is now being updated on a rolling basis so you’ll still receive updates even if you don’t register.

Adverts for Avast’s paid-for products are unobtrusive. They concern adding features such as a firewall, data shredder, system cleanup utility, a VPN and a sandbox mode that allows you to run suspicious programs in a virtual environment, cut off from your main PC.

Avast tries to install the SafePrice browser extension – a price-comparison pop-up generator that we recommend rejecting or removing if it attempts to add itself to any of your web browsers. It’s a bit cheeky to attempt to add what’s effectively an ad platform – but in the world of free AV, anything goes.

There’s also a rather more useful Online Security plugin, which scans websites for malware and blocks ad-trackers. Most modern browsers have this sort of privacy built in, although you might find you trust Avast-branded software more than your browser.

It also hooks into Avast’s free SafeZone sandboxed browser, which is designed to help protect you against data-stealing “man-in-the-middle” attacks when using services such as online banking websites. SafeZone can also be opened via Avast’s notification area icon.

Delving into Avast’s settings will allow you to add URLs that you’d rather it didn’t scan, enable a pop-up-free silent mode (Avast now also automatically tries to detect games so as not to interrupt you in the middle of a critical boss fight), manually check for updates, set up email alerts to be sent if malware is detected, add annoying-but-not-damaging potential unwanted programs to its scans, disable sound alerts, or enable the program’s extra-paranoid Hardened mode.

Other Avast Free features are available in the client’s Protection, Privacy and Performance tabs. As you’d expect, you can run a variety of full and partial virus scans; view previously detected viruses; enable and disable Avast’s automatic file, web and mail scanning; scan your network for potential vulnerabilities; and create a rescue disk in case malware prevents your system from booting correctly at any point.

Avast also has a free built-in password manager that has an online vault and apps for Windows, macOS, Android and iOS. However, since it’s integrated into your antivirus software, we’d advise that you stick with a dedicated password management software so you don’t have to go to the trouble of exporting your data and switching manager if you wish to switch to a new AV product.

Protection and performance

Avast performed well in the latest virus protection tests carried out by both AV-TEST and SELabs, identifying 100% of malware in two of AV-TEST’s real-world exposure tests, and 99.8% and 99.9% in successive months’ tests against a reference set of recent viruses, earning it a 6 out of 6 protection score from the testing firm. AV-TEST saw only three false positive detection warnings in a set of over a million legitimate content test samples, netting another 6 out of 6 score.

It also put in a good performance in SELabs’ real-world detection tests, protecting against 89% of malware in a challenging live test environment that included both general threats and targeted attacks and registering no false positive detections of legitimate software.

It was relatively quick to run a full malware scan on our reference system, taking just under 17 minutes, and we found that didn’t affect system performance too badly when running CPU-Z’s processor benchmarks, although it didn’t perform quite as well on that front as rival Avira or – unsurprisingly – Microsoft’s integrated Windows Defender. AV-TEST’s more involved system performance tests found that Avast’s Windows 10 performance improved on previous months, and awarded it a score of 5 out of 6.

Avast Free Antivirus 17 is one of the best best free anti-malware products around right now, although it’s been pipped into second place this time around thanks to the release of Kaspersky Free Antivirus.

Avira Free Antivirus 2017

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Key features:

  • Can create bootable rescue disk
  • Windows 7/8/8.1/10


A great lightweight free AV product

Avira Free Antivirus 2017 comes with a range of extra utilities, which are all accessible via the Avira Connect client, which lives in your notification area and is designed to provide quick access to everything.

It shows your protection status, with tabs displaying any other devices you may have associated with your Avira account – assuming you’ve signed into it – and one that gives you the option of upgrading the free tools to one of Avira’s paid services. Quick-access buttons allow you to rapidly enable a VPN or run a quick virus scan.


The complete set of Avira Connect tools includes Free Antivirus, a password manager; the free version of Avira Phantom VPN and System SpeedUp; and, optionally, Avira’s SafeSearch Plus sponsored search engine. You can use the latter as your browser’s default search and it will show only links that Avira as passed as safe – but we don’t generally recommend restricting your results by using sponsored search services of this kind. Plus, Google has become pretty good at eliminating dangerous links, so this addition seems overkill.

While these services and extensions are available by default when you install Avira Free, you can remove those that you don’t want to cut down on clutter. That includes the Avira Connect application itself – so if all you want is antivirus, you can make sure that’s all you have. This is worth keeping in mind if you want to use Avira on an older or less powerful PC.

Open up Free Antivirus and you’re presented with a slightly old-fashioned, cluttered but clearly labelled interface, from where you can run scans and enable and disable various modules. Unfortunately, in general the interface feels sluggish and slow to respond, particularly when it comes to options that spawn new windows.

Since this is the free version of Avira, numerous options are greyed out. For example, only default Internet Protection is available, without dedicated Web Protection or Mail Protection options, and there’s no pop-up-free Game mode in this version.

The Firewall settings plug directly into Windows Firewall, but make it easier to find critical settings for this than Windows 7’s own interface. An Android Security option on a tab pane to the left of the Antivirus window is just an advert for the company’s smartphone antivirus protect. However, the left-hand pane provides clear and quick access to reports, event logs and quarantined files, which are all easy to find – a welcome feature that many rivals try to hide under the bonnet to avoid intimidating inexperienced users.

The real-time protection tab will also provide stats on anything Avira has picked up on your system, while the System Scanner lets you run a variety of full, custom and predefined scans on active processes, local and removable media.

Avira Phantom VPN’s free iteration gives you 500MB of bandwidth on the service; you can register for free to increase that to 1GB, or pay £7 a month for a Pro subscription. Finally, Avira System Speedup free provides a few system optimisation tools, although we prefer the free version of Piriform’s CCleaner for the job.

Protection and performance

The Avira malware detection engine scored well in AV-TEST’s May and June 2017 tests, with 100% and 99% in real-world live malware exposure trials, and 100% detection rates when scanning a reference set of recent malware. This earned it an AV-TEST protection score of 6 out of 6. SELabs did not include Avira in its latest tests, so we have no other test data in this instance.

Avira is one of the lightest-weight free antimalware programs in terms of its impact on system performance. AV-TEST agave it a performance score of 6 out of 6. Meanwhile, our benchmark performance tests on a 2.1GHz dual-core system with 8GB RAM revealed that only Microsoft’s integrated Windows Defender had less of an impact on system performance. A full system scan took 26 minutes and 20 seconds.

Avira provides effective malware protection and is less of a resource hog than many of its free and paid-for rivals, making it a good choice for older PCs, particularly those running Windows 7, 8 or 8.1, which don’t have access to the improved Windows 10 Creators Update version of Windows Defender.

AVG Antivirus Free

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Key features:

  • Email scanning module
  • Bootable rescue disk available as separate download
  • Windows XPSP3/Vista/7/8/8.1/10

Like most antivirus packages, AVG Antivirus Free comes with a front-end utility for a whole suite of optimisation and monitoring tools. It can be linked to an online account that will allow you to view the status of multiple devices with AVG installed on them, including both computers and smartphones.


Unlike some of its rivals, AVG by default installs only the main antivirus package, saving on irritating clutter. However, it’s still necessary to click through from the general AVG client to access Antivirus Free to so much as view your protection status – which feels like a redundant extra step if you don’t use any of AVGs other products or services.

Accessible from the console too are AVG PC TuneUp, a paid-for system optimisation software that’s available on a one-day trial licence; AVG Secure VPN, available on a 30-day trial; and AVG Web TuneUp, a browser plugin with search safety ratings and ad-tracking blocking features. This is free, but also changes your default search engine, homepage and other browser settings, which you may prefer to control yourself.

Once you’ve clicked through from the general AVG client to Antivirus Free, you’re presented with a quick overview showing your protection status, the time of your last scan and update, a quick-scan button, and a couple of relatively unobtrusive adverts for AVG’s full Internet Security package.


The client fits in well with the default dark tones of Windows 10’s Modern UI. AVG Free provides real-time protection and scheduled or on-demand scanning, but the client makes it clear that it’s missing some features from its paid-for version.

These include AVG’s Enhanced Firewall – no great loss, given how capable Windows Firewall is; an encrypted data safe similar to that provided by free encryption tool VeraCrypt and Microsoft’s BitLocker; anti-phishing and DNS spoofing detection features.

However, all the core protection you need is included. Extra settings and options are available via a menu at the top right of the window, including a file shredder to delete items so that they can’t be recovered, plus access to your quarantined files.

Additional settings let you enable a pop-up-free silent mode if you’d rather not be bothered when your antivirus detects anything; disable email signatures marking email sent from a desktop as scanned; and individually customise the sensitivity and behaviour of AVG’s email, web, software and real-time scanning components.

Protection and performance

AVG is one of the most popular free antimalware suites around, but and the latest results for its detection engine from both AV-TEST and SELabs have shown improvement since the beginning of 2017. In May and June, AVG got 100% in AV-TEST’s real-world live malware exposure tests, and 99.8% and 99.9% when it came to detecting malware from a large reference set, earning it an overall protection score of 6 out of 6. It threw up only a couple of false positives in response to over a million samples.

In SELabs’ tests involving live exposure to both in-the-wild and targeted attacks, AVG got a protection score of 88%: a marked improvement on the last round of tests, putting it ahead of the engine used by Windows Defender. It got a total accuracy score of 96% when taking false positive detections of benign software into account – an important factor in usability, particularly for those who are less tech-savvy.

It took just 14 minutes and 35 seconds to run a full malware scan on our reference system, but had a somewhat heavier system load than some of its free rivals.

After a slight dip in detection performance in early 2017, AVG has returned for form, proving that it still provides a good level of protection. It’s easy to use and a good choice for users who don’t want to have to worry about unwanted ‘bonus’ features.

Comodo Free Antivirus

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Key features:

  • Sandbox module
  • Bootable rescue disk available as separate download
  • Windows XP SP3/Vista/7/8/8.1/10 (Linux and MacOS products also available)
  • Requires minimum 152MB RAM, 400MB disk space

Comodo’s Free Antivirus is a longstanding favourite among those who like a highly configurable free product with extra tools designed to help them block and diagnose potential malicious files.


Of particular note are Run Virtual: a tool that allows you to run any program you like in a sandbox with restricted access to the rest of your system, and Comodo’s Host Intrusion Protection System – disabled by default – which provides extra monitoring against suspicious activity, but may prompt you to manually give some programs permission to run.

The Comodo client’s main interface is cleanly designed, showing your current protection states and including large buttons for four key features: scanning; updating the Comodo client and signatures; unblocking applications that Comodo has restricted access to as suspicious programs; and starting the Run Virtual sandbox.

The sandbox provides a virtualised environment means that you can run unfamiliar software in, providing some peace of mind if you’re suspicious of a program.

An alternative Advanced View interface is available for the client, summarising currently active modules and detected threats and including a drag-and-drop scanner for specific files. Both standard and advanced interfaces include a Silent Mode button that will entirely disable all alert pop-ups, which is handy if you don’t want to have your anti-malware program grabbing screen focus when you’re playing a game.

When installing Comodo, you’ll want to take care to uncheck boxes changing your default search engine to Yahoo and your default browser to Comodo Dragon, which is automatically installed as part of the antimalware suite but can be manually uninstalled.

A desktop widget is activated by default, including shortcuts for Comodo’s various features, installed browsers and popular social media sites – while some might find it useful, we deactivated it in Comodo’s settings. You’ll probably also want to disable audio alerts.

When you uninstall Comodo, you’ll have to separately uninstall its Internet Security Essentials man-in-the-middle attack defence package, as well as the Dragon browser, and tell you don’t want to switch to using its lightweight Cloud Antivirus.

Protection and performance

We only have AV-TEST results for Comodo, but these show good malware detection performance in both real-world live exposure tests, with a 100% detection rate in May and June, and scans involving thousands of malware reference samples, with 100% and 99.9% detection rate across the same two-month test period. Its false positive rate was variable, with six detections of legitimate software as potentially malicious in June, but none in May.

However, its performance load was conspicuously bad, slowing down the loading times of websites by a massive 47% on a high-end PC, and increasing file copy speeds by a massive 211% on the same system. While it provides effective malware defense, it’s hard to recommend when rivals such as Avira, Avast and Kaspersky Free provide comparable or better levels of protection with a fraction of the impact on your PC’s smooth running.