Avast Antivirus Free review: Our free favourite for older Windows PCs

Effective free antivirus that’ll work on operating systems all the way back to Windows 7

IT Pro Recommended
A screenshot of Avast Antivirus Free
  • Free
  • Effective malware protection
  • Works on older versions of Windows
  • Mishandled user data for marketing purposes in the past
  • Slightly less accurate than Windows Defender in recent tests

Avast provides both free and paid-for security software under a variety of brands, but is best known for Avast Free Antivirus. The company also owns erstwhile rival AVG, and the two product ranges share the same malware detection engine. However, Avast provides a more polished interface and a particularly good range of features.

Free third-party antivirus suites now primarily serve as an alternative to Microsoft Defender, which is extremely good at realtime malware defence and is built into Windows 10 and 11. However, if you have a slower PC that might benefit from more streamlined software, or if you’re using an older version of Windows (such as 7 or 8.1) that’s no longer supported with updates from Microsoft, Avast is an excellent choice.

As well as realtime virus detection and on-demand scanning, Avast includes dedicated protection against threats via the web, your local network, local files and attachments received via your desktop email client. You also get ransomware protection, which prevents unauthorised changes to selected directories. 

Avast’s performance across recent tests by SE Labs, with 100% total protection rating, and AV-Comparatives, where it defended against 99.7% of malware, put it on a par with Microsoft Defender, which has become a benchmark for effective and unobtrusive malware protection in recent years.

Unusually, Avast’s performance slipped slightly in the latest (July - August 2021) tests by AV-Test, dropping to 99.9% protection against a reference collection of recent malware samples in August. However, it still aced the critical real-time protection test, which tests its ability to defend against malware as it might be encountered in the wild. It also flagged only one benign file as a false positive.

Avast did well in AV-Test’s system performance impact tests, and had less of an impact on software install times than Microsoft Defender, particularly on low-spec systems, although it did slightly worse on website load times, launching software and copying files.

You don’t need to create an Avast account to use the free service. However, if you do register, you can also sign up for free alerts if your email address is included in a breach. 

Avast’s free product exists to support its paid-for software, both by sending back data about new viruses that users might encounter and by directly promoting products by Avast and its partners, but this isn’t particularly obtrusive. As far as partner promotions go, we were invited to install Google Chrome alongside Avast at installation. Once you’re running Avast, you’ll encounter a few more promotional messages. A small “Go premium” button lurks at the bottom of the interface’s sidebar and a bottom bar prompts other avast products. Promotions for Chrome may also appear in Avast’s software updater if you don’t have it installed. 

Elsewhere, features that are only available in the paid-for version of the software are marked with a lock symbol. Click on them, and you’ll be prompted to upgrade. These restricted features include webcam protection, a dedicated firewall, a sandbox to run suspicious applications, and a few other tools and features that aren’t available to free users.

You do get access to a couple of extra tools in Avast’s Performance section: a software updater and a do not disturb button to keep your antivirus software from interrupting when you’re playing a game or watching a film at full screen. 

An optional anti-tracking and online reputation checking browser extension, Avast Online Security, is also available from Avast, as is the fully branded Chromium-based Avast Secure Browser. Neither of these is our preferred anti-tracking tool - uBlock Origin is a lightweight and effective alternative. Avast has shut down its Jumpshot market analytics subsidiary, which was found to be using data about Avast customers’ browsing habits as part of its product, but we’re nonetheless disinclined to recommend handing that information over.

Despite that spot of dubious data handling, which has now been publicly resolved, Avast remains a lightweight and effective malware protection solution, especially for older PCs.

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