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Windows 10 full protection

Get your Windows 8.1 PC running smoothly

We’re more than just free antivirus. Avast also protects your Windows 8.1 PC’s performance, using cloud-based processing to secure you without slowing you down. In addition, you can optimize Windows 8.1 with Avast Cleanup, which will adjust settings, clear junk data, and clean out your registry to get your Windows 8.1 PC running as good as new.

Safe upgrade to Windows 10

Essential antivirus protection for Windows 8.1

Avast Free Antivirus has been tested on Windows 8.1 by AV Comparatives, who found we offer 100% protection against zero-day malware attacks. That, combined with our growing suite of security features such as Avast SecureLine and Avast Passwords, will ensure that no threat will put you or your PC at risk.

Approved antivirus for Windows 10

Microsoft-approved security for Windows 8.1

Avast is one of Microsoft's official consumer security software providers – ensuring our place as one of the most beloved, trusted antiviruses on the net, used by 400 million users around the globe.

Avast Antivirus is compatible with Windows 11, 10, 8.1, 8, 7, Vista, XP SP3

Avast also offers you security solutions for your Android and Mac

The people have spoken

And we want to hear from you too. The more feedback we get, the better we’ll be able to serve and protect you from malicious software — after all, isn’t that why we’re here?

Avast Free Antivirus for Windows 10



It's clean, easy, and works.

Avast Free Antivirus for Windows 10



It's very easy program

Avast Free Antivirus for Windows 10



easy to used < its the best

Avast Free Antivirus for Windows 10



I love Avast, I have used it for at least 5 years or maybe more. will continue to do so

Avast Free Antivirus for Windows 10



easy to used < its the best

Avast Free Antivirus for Windows 10



easy to use and download

Avast Free Antivirus for Windows 10



I love that it protects my computer, cell phone, and even my iPod. And I only have to have one account! Super easy

Avast Free Antivirus for Windows 10



Years and years using this software, I like it and lots of friends and family are using it too. If your computer is infected it goes straight to the base of your O.S. and kill the virus. Love it !

Avast Free Antivirus for Windows 10



It is the best antivirus on the market. Very efficient and easy to use. Would definitely use again and again.

How to install Avast Antivirus for Windows 8.1

It’s easy to start protecting your PC or laptop against viruses and malware with the latest version of Avast antivirus for Windows 8.1.

Just follow these easy steps:

1Download the installer by clicking here.

2Right-click the installer and click “run as administrator”.

3Click “Install”.

4When the progress bar vanishes, your device is protected.

And that's it! Your device is now secure.


Does Windows 8.1 need an antivirus?

Every PC needs protection and Windows 8.1 PCs are no exception. Windows 8.1 does have built-in security software, however, it is widely accepted that this built-in security is not enough. Therefore for better online security, you need a third-party antivirus to keep you safe from viruses, ransomware, and other malware.

Does Windows 8.1 have Windows Defender?

Windows 8.1 does have Windows Defender built-in, however, it only offers basic protection to Windows 8.1 PCs. Therefore, for true online security, it would benefit you and your device to invest in third-party antivirus software that can make up for the limitations of Windows Defender.

Is there a free antivirus for Windows 8.1?

Yes. Windows Defender is free, as it comes built-into Windows 8.1. However, if you’re looking for more comprehensive security software, Avast offers a free antivirus for Windows 8.1. The free version of Avast Antivirus for Windows 8.1 provides powerful and comprehensive protection that should more than suffice for your needs. If you would like more security, however, you can also download a 30-day free trial of Avast Premium.

What makes Avast one of the best antiviruses for Windows 8.1?

Avast Free Antivirus for Windows is one of the best Windows antiviruses by far due to our powerful security and additional features. We use six layers of security to ensure you have protection from 0-day threats. Additionally, our automatic spyware removal tool can keep your data private, and we make removing viruses already on your Windows 8.1 PC easy. Best of all, we’re absolutely free, so you can download and install our protection without paying anything.