Best Free Antivirus Software

What separates the best free antivirus picks?

Three names made the cut, and the scores are close: Microsoft Defender at 8.1, Avast One at 7.7, Malwarebytes Premium at 7.7. The gap is in what you get for the money.

Defender is already on every Windows PC and costs nothing to keep. It caught 98% of our samples and scores 6/6 in AV-Test. SmartScreen phishing protection in Edge is a real bonus. Outside Edge, phishing protection drops — it caught 41 of 50 URLs. There is no Mac protection outside the Microsoft 365 app.

Avast One's free tier includes real-time protection, a firewall and 5 GB of VPN a week. It caught 99% of our samples. The paid tier is $49.99 and adds cleanup and driver tools. Two things to weigh: upsells inside the free version, and the fact that Avast paid $16.5 million to the FTC in 2024 over selling browsing data through Jumpshot.

Malwarebytes Premium is $59.99 and removed every adware and potentially-unwanted program on our infected test image. Browser Guard blocks scams and trackers, and the renewal price matches the first year. It missed 3% of our samples on first contact, and labs score it slightly below the leaders. Extras are few.

What should you check before buying?

Scoring weights protection at 35, performance at 20, value at 20, features at 15 and usability at 10. That tells you where the differences show up.

• Protection: Defender caught 98% of samples, Avast One 99%, Malwarebytes missed 3% on first contact.
• Value: Defender is free with nothing to renew. Avast One is $49.99. Malwarebytes Premium is $59.99 with the same price at renewal.
• Features: Avast One's free tier bundles a firewall and 5 GB of VPN a week. Malwarebytes adds Browser Guard. Defender leans on SmartScreen in Edge.
• Usability: Defender needs no install. Avast One shows upsells. Malwarebytes is built for cleanup.

Microsoft Defender

For anyone on Windows who wants protection without installing or renewing anything. Skip it if you browse outside Edge and want stronger phishing cover, or if you need Mac protection.

Avast One

For shoppers who want a free suite with a firewall and a weekly VPN allowance, and who don't mind upsells or the company's 2024 FTC settlement over browsing data.

Malwarebytes Premium

For anyone cleaning up adware or unwanted programs, or who wants Browser Guard and a renewal price that doesn't jump. Accept the 3% first-contact miss and the thin extras.

Microsoft Defender suits Windows users who want free protection with nothing to install or renew. Avast One fits shoppers who want a free firewall and 5 GB of VPN a week and can live with upsells. Malwarebytes Premium is the pick for cleaning up adware and unwanted programs, with Browser Guard and a renewal price that matches the first year.