Below is a list of all the best free bootable antivirus programs that I could find. If you don't know what these are, they are simply virus scanners that boot from a disk or flash drive instead of your computer's hard drive.

After trying dozens of bootable virus scanners, these represent our favorite free options:

Microsoft Defender Offline (formerly Windows Defender Offline) is a bootable antivirus scanner from Microsoft with a full user interface. It is built into Windows 11 and Windows 10, and you can download it for older Windows versions or newer ones if your computer won't boot.

One important feature I like is that the definitions (the rules for finding threats) can be updated directly from disk, which many bootable virus scanners cannot do. You can also view quarantined files and exclude files, folders, and extension types from scanning.