Antivirus software exists to catch malicious code before it runs, and to clean up if something slips through. On Windows 11, Microsoft Defender is already installed, enabled, and updated daily, which changes the real question from "which antivirus do I need" to "what does Defender not cover for me" — usually on-demand second-opinion scanning, ransomware rollback, or centralized management for a small fleet of machines.
macOS has its own built-in protections — Gatekeeper, XProtect, and notarization checks — that block a large share of known Mac malware before it launches. Third-party Mac antivirus tools mostly add value by scanning for cross-platform threats, such as malicious files a Mac user might forward to a Windows-using colleague.
We document each tool's publisher, official download location, and what independent testing labs have actually measured, rather than repeating marketing claims about detection rates.