AV-TEST Institute tested 21 antivirus products over 6 months. In the Windows consumer category, Kaspersky Internet Security and Norton 360 tied for top score of 18/18, both achieving 100% protection against zero-day attacks and 99.9% against widespread malware. Bitdefender Internet Security achieved 17.5 points. Avast Free Antivirus achieved a strong 17 points. Microsoft’s Windows Defender achieved 17 points. The performance category showed Webroot SecureAnywhere and ESET NOD32 with the lightest system impact. Our analysis includes AV-TEST’s methodology, detailed breakdowns, and recommendations based on your priority.