Best free antivirus 2015: What is the best free internet security software?

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What's the best free antivirus packages on the market? Read our round-up to find out

They say you don’t get something for nothing, but when it comes to protecting your PC against online threats that's not necessarily the case. There are numerous completely free antivirus tools out there that can automatically block malicious code, and actively scan the files on your PC to make sure you’re not unknowingly harbouring something nasty. In this article we bring to you the best free antivirus packages of 2015 to keep your PC safe.

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For many, the default option is Microsoft Security Essentials (you may know this as Windows Defender - it was renamed in Windows 8). Depending on the version of Windows you’re running, this will either come preinstalled or will be offered to you through Windows Update.

As antivirus programs go, Security Essentials is as straightforward as things get: most of the time you won’t even know it’s there, and it has very little impact on the responsiveness of your system.

In our independent tests, however, it allowed more than the odd bit of malware to slip through the cracks – so it’s worth considering picking a third-party alternative.

Third party tools will almost certainly offer better protection than the default Windows offering, but that's not the only advantage they provide. They should also deliver more features, such as browser cleanup tools, software updaters, and even rescue disk creation tools for when things get really bad.

Best free antivirus 2015: packages compared

One well known option is AVG AntiVirus Free, which has been providing free virus protection since the 1990s. The modern AVG client actively detects and blocks viruses, and also integrates with your browser to warn you away from known dangerous websites.

On low-power hardware, however, its scanner has a noticeable impact on the responsiveness of the system it's running on. Although it’s free to download and use, the sheer amount of in-program advertising is irritating. And malware protection isn't the best around, either.

We've also included Qihoo's 360 Safe in our annual roundup this year, and it proved a suprise package in our tests. It's different from most free antivirus packages in that it uses two malware detection engines, resulting in a very high protection rating of 99%. It's intuitive to use, too, but that extra AV enging does have a negative aspect in that it's quite hard on system resources.

Our favourite free antivirus tool of 2015, however, remains Avast Free Antivirus - the same as last year. In our tests this package gained not only an impressively high protection rating, but it also allows most legitimate applications to install, even obscure ones. You also get a host of secondary tools, including a silent mode to prevent pop-ups during gaming and a hardened browser to protect inexperienced users.

Avast is also light on resources and shouldn’t noticeably slow your PC down; and although, like AVG, the front-end includes advertisements for paid-for products, these are much less plaintive. For all these reasons, Avast Free Antivirus 2015 is our recommended free antivirus package.

Best free antivirus 2015

1. Avast Free Antivirus 2015

Avast Free Antivirus 2015 review - main UI

The best of the free security suites, Avast's likeable offering brings effective virus protection in a lightweight yet well-equipped package.

Read the full Avast Free Antivirus 2015 review here.

2. 360 Safe

Employing twin antivirus engines and a friendly, intuitive interface, 360 Safe provides the best protection of any free package we've tested.

Read the full 360 Safe review here.

3. AVG Antivirus FREE 2015

AVG Antivirus Free (2015) review - main interface

A free virus scanner with more adverts than useful features, plus its malware protection lags well behind the best free packages.

Read the full AVG Antivirus FREE 2015 review here.

4. Microsoft Security Essentials

Microsoft Security Essentials 2015 review - interface

Security Essentials covers only the bare basics of malware protection, and allowed alarmingly high percentage of attacks to succeed in our tests. If you value the safety and security of your PC, you'll install a third party package to boost your protection levels.

Read the full Microsoft Security Essentials (2015) review here.

How we test

Each package's core anti-malware features are tested at the staet-of-the-art facilities of Dennis Technology Labs. Rather than artificially infecting our target systems, we set them up in an environment that mimics how our PCs become infected in the wild, to get an accurate picture of how each security pageage fends off malware in real-world situations.

We look at whether the package provides protection, and also how it handle each threat. The resulting data informs a protection rating of up to 100%. Meanwhile, we also install legitimate software to see what the security packages block and where they prompt for user intervention, factoring in the obscurity or otherwise of the application. We award a second score for false positives, where 100% represents a perfect record.

After formal testing, we run through each package to check its other features and get a feel for its usability and its burden on system resources. We measure the latter by monitoring RAM and CPU consumption over the course of basic scan, also timing how long these scans take to complete. All this information is factored into the final, Overall star rating you'll see at the top of each review.

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