Best Free Antivirus Software 2026: 6 Options Compared

On a Windows PC, the free antivirus you already own is a strong baseline. Microsoft Defender Antivirus is built in, runs in the background and needs no account, and independent labs generally rate it close to paid suites, so the honest question is what a second free product adds. Avast Free Antivirus and Avira Free Security bundle extras such as a password manager or capped VPN, and their paid plans are pushed hard, so expect upgrade prompts. Bitdefender Antivirus Free keeps the interface simple but covers Windows only and needs a Bitdefender Central account. Malwarebytes Free is best used as an on-demand second opinion, since the free edition has no real-time protection per a TechRadar review. ClamAV is an open-source scanner for Linux servers and mail gateways and has no desktop real-time shield on its own. The trade-off is nagging versus convenience: free third-party products fund themselves through upsells and sometimes data, so read the privacy settings at install. On Mac and phones the picture changes because built-in protections do more of the work, and free scanners matter less. Never run two real-time antivirus engines at once, because they conflict.

Microsoft Defender Antivirus

Built into Windows with no extra cost, Windows only, and central management needs a paid Microsoft product. For most home users it is the baseline to beat.

Price: Free (built into Windows) (Microsoft Defender Antivirus pricing, checked 2026-10-22).

Platforms and license: Windows. Proprietary.

Best for: Default protection on Windows.

Worth knowing: Windows only; central management needs a paid Microsoft product.

Bitdefender Antivirus Free

Free for Windows with real-time protection and basic ransomware protection, plus a VPN capped at 200 MB per device per day. Needs a Bitdefender Central account; Mac and mobile need paid plans.

Price: Free (Free for Windows with real-time protection and basic ransomware protection; VPN capped at 200 MB per device per day) (Bitdefender Antivirus Free pricing, checked 2026-10-23).

Platforms and license: Windows. Proprietary.

Best for: Simple Windows protection.

Avast Free Antivirus

Free antivirus for PC, Mac and mobile, with some features locked to paid plans. Check the vendor site for the current platform list.

Price: Free (Free antivirus for PC, Mac and mobile; some features need a paid plan) (Avast Free Antivirus pricing, checked 2026-10-23).

Platforms and license: Windows, macOS, Android, iOS. Proprietary.

Best for: Multi-platform households.

Avira Free Security

Free antivirus, password manager and a VPN limited to 500 MB per month, on Windows, macOS, Android and iOS. Its official page was blocked, so details come from search snippets.

Price: Free (Free antivirus, password manager and VPN capped at 500 MB per month) (Avira Free Security pricing, checked 2026-10-23).

Platforms and license: Windows, macOS, Android, iOS. Proprietary.

Best for: Bundled extras on a budget.

Malwarebytes

Free scanner for Windows, Mac, Android and iOS, but per a TechRadar review the free edition lacks real-time protection. Use it to double-check a machine, not as the only shield.

Price: Free (Free malware scanner; per a TechRadar review the free edition has no real-time protection) (Malwarebytes pricing, checked 2026-10-23).

Platforms and license: Windows, macOS, Android, iOS. Proprietary.

Best for: Second-opinion scans.

Compare: Malwarebytes alternatives

ClamAV

GPL-2.0 scanner with signature updates, for Linux, Windows and macOS. It has no central console or behavioural detection, so it fits servers and mail scanning more than desktops.

Price: Free (ClamAV pricing, checked 2026-10-22).

Platforms and license: Linux, Windows, macOS. GPL-2.0 (open source).

Project activity: 7.5k GitHub stars · latest release clamav-1.5.4 (Aug 7, 2026) · last commit Oct 22, 2026

Best for: Linux servers and mail scanning.

Worth knowing: Scanner and signature updates only; no central console or behavioural EDR.

Which one to pick

• You use Windows and want zero setup: Microsoft Defender Antivirus
• You want a lightweight Windows tool with real-time protection: Bitdefender Antivirus Free
• You suspect an infection and want a second opinion: Malwarebytes
• You run a Linux file or mail server: ClamAV
• You need free cover for a Mac as well as a PC: Avast Free Antivirus