Best Free Antivirus 2017: Avast, AVG, Avira and Windows Defender tested

Best Free Antivirus 2017: We look at the four best free anti-malware solutions on the market right now.

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.

Related: Best VPN

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 Xeon 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 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”.

Microsoft Windows Defender

1 of 4


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 now 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 for 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

Windows Defender uses the same malware detection engine as Microsoft Security Essentials for Windows 7, and AV-TEST and SE Labs’ results were obtained from that version. It put in an impressive performance in AV-TEST’s recent real-world testing, scoring 100% in both January and February.

When it came to detecting malware in a reference set of samples, it picked up 99.3% in January and 99.6% in February. It also did well in AV-TEST’s false-positive test, with only three false detections from over a million samples of benign software. It scored 84% in SE Labs’ live malware exposure tests, and avoided most false positives, giving it an overall score of 94%.

While AV-TEST found that Security Essentials under Windows 7 had a notable impact on system performance, giving it a score of 5 out of 6, in our simple performance test of a PC running Windows Defender with real-time protection enabled it produced a small performance boost when compared to other free antivirus suites. Running a full malware scan on our reference system took a somewhat extended 32mins 33secs.

Regardless of your feelings about its tendency to phone home, and the software-as-a-service-style limitations it places on user control over OS features such as upgrades, Windows 10 is Microsoft’s most secure operating system to date. With that in mind, Windows Defender could one day become the only antivirus you need, rather than an option of last resort.

If you’re running the latest version of Windows 10, Defender has grown into a surprisingly capable set of protection tools that have minimal impact on system performance and – of course – blend in perfectly with the look and feel of the operating system. We also look forward to seeing if the new version of Defender is accompanied by any improvements to Microsoft’s malware detection engine – relevant data is, for now, unavailable due to the newness of the product.

If you want to try it, though, we recommend doing so from a clean Windows installation; it can be challenging to re-activate Defender after removing other antivirus software, since it often responds to leftover registry settings by disabling itself so as not to interfere with any rival products.

Avast Free Antivirus

2 of 4


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

The best free Antivirus software

Avast’s Free Antivirus product has been slimmed down and polished up since we last reviewed it in summer 2016. A clean, dark interface sits 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. Now ‘registration of the latest version of Avast Free Antivirus is no longer necessary.’

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.

The company informs us that all traces of the old registration system will be removed in the near-future, and that they can safely be ignored for now. If you have other devices running Avast products, registering them all to the same account will allow you to view the protection status of them all, but provides no other major benefits.

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 SE Labs, identifying 100% of malware in two of AV-TEST’s real-world exposure tests, and 100% 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 a single false positive in a set of more than a million tests, netting the firm another 6 out of 6 score.

Avast was the best-performing free antivirus package in SE Labs’ real-world detection tests, protecting against 87% of malware in a challenging live test environment that included both general threats and targeted attacks. However, a couple of false positive responses to legitimate software gave it a relatively low total accuracy rating of 92%.

It was quick to run a full malware scan on our reference system, taking just under 17 minutes, and we found that it 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 was a relatively poor performance compared to most of its free rivals, giving it a rating of just 4.5 out of 6.

Despite this, Avast Free Antivirus 17 is the best free anti-malware product around right now. If you need to squeeze a little more performance out of a low-powered system, Avira is a good alternative, however.

Avira Free Antivirus 2017

3 of 4


Key features:

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

A great lightweight free AV product

Avira comes with a range of extra features that are all accessible via the Avira Connect utility, 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.

The extra features in Avira’s toolkit include the company’s new stand-alone password manager. It’s based around a web dashboard, browser plugins and mobile apps, and Avira is providing Pro features for free until May 2017. After this, free users won’t be able to sync passwords across multiple devices, so you’ll need to commit or move on after that.

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 AVLabs’ January and February 2017 tests, with 98.9% and 98.1% in real-world live malware-exposure trials, and 99.8% and 99.9% detection rates when scanning a reference set of recent malware. This earned it an AV-TEST protection score of 5 out of 6. It reported no false positives during AV-TEST’s latest test.

Avira is one of the most lightweight free anti-malware programs in terms of its impact on system performance. AV-TEST gave it a performance score of 5.5 out of 6. Meanwhile, our CPU-Z benchmark performance on a 2.1GHz dual-core system with 8GB of RAM revealed that only Microsoft’s integrated Windows Defender had less of an impact on system performance. A full system scan took 26mins 20secs.

Avira provides effective malware protection and is less of a resource hog than many of its free and paid-for rivals, making it a great 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

4 of 4


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 of the features of 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 anti-malware suites around, but recent performance of its detection engine in tests by both AV-TEST and SE Labs has been slightly disappointing. In January and February, it achieved detection scores of 98.9% and 98.1% 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 a protection score of 5.5 out of 6. It threw up only a couple of false positives in response to over a million samples.

In SE Labs’ test, involving live exposure to both in-the-wild and targeted attacks, AVG got a protection score of 83% – which is fair, but lower than those of either Windows Defender or Avast Antivirus Free. However, AVG was boosted to a total accuracy score of 93% when taking false-positive detections of benign software into account – an important factor in terms of usability, particularly for those who are less tech-savvy.

It took just 14mins 35 secs to run a full malware scan on our reference system, but it had a somewhat heavier system load, as measured by CPU-Z’s benchmark performance. However, AV-TEST’s more involved tests found that it was on a par with lightweight Avira for performance.

Although it’s proved slightly less effective than its free rivals in tests over recent months, AVG still provides a good level of protection, and we found it easy to use. It’s a particularly good choice for users who don’t want to have to worry about unwanted ‘bonus’ features.

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