StackAnalyst

Kaspersky consistently scores at the top of independent lab tests for its excellent malware detection rates. Its free version provides robust real-time protection against viruses, spyware, and phishing. While its free offering is more streamlined than its competitors, it focuses on doing one thing exceptionally well: stopping malware.

• Strengths: Top-tier malware protection scores, low impact on system performance, clean interface with minimal upselling.
• Best for: Users who want the most effective free malware protection and prefer a no-fuss, set-it-and-forget-it security tool.

AVG has been a household name for decades. Its free antivirus includes not just malware protection but also an email shield and a file scanner. While its protection is solid, AVG is known for having a slightly heavier system impact and more frequent pop-ups encouraging users to upgrade to its paid security suite.

• Strengths: Good malware detection, includes extra features like email scanning, long-standing reputation.
• Best for: Users who want a few extra security features beyond basic malware scanning and don't mind occasional upgrade prompts.

Since acquiring AVG, Avast shares the same underlying antivirus engine, resulting in similarly strong protection scores. Avast Free Antivirus comes with a modern interface and a host of extra tools, such as a Wi-Fi network scanner and a password manager. Like AVG, it uses its free product to heavily promote its paid versions.

• Strengths: Strong malware protection, includes useful extras like a network scanner, modern and user-friendly interface.
• Best for: Users looking for a comprehensive free security toolkit and a modern user experience, who can tolerate upsell notifications.