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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 people around the globe.

Avast 防毒軟體與 Windows 108.187VistaXP SP3 相容

Avast also offers you security solutions for your Android and Mac

很多人都分享了自己的經驗

我們也希望您說說自己的看法。得到越多意見反應,我們就能提供更好的服務,更清楚如何為您抵禦惡意軟體攻擊─畢竟,這不就是我們的目標嗎?

Avast Free Antivirus for Windows 10
5

It's clean, easy, and works.

Avast Free Antivirus for Windows 10
4

It's very easy program

Avast Free Antivirus for Windows 10
5

easy to used < its the best

Avast Free Antivirus for Windows 10
5

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
5

easy to used < its the best

Avast Free Antivirus for Windows 10
5

easy to use and download

Avast Free Antivirus for Windows 10
5

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
5

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
5

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