RansomWhere? analyses file entropy in real time to notice when a process starts encrypting your files, then flags and stops it before it can do serious damage. It runs on macOS 10.15 and later.
Made by Objective-See; the source is GPL-3.0.
Honorary mentionLiveOpen source
RansomWhere?
Spots ransomware on a Mac by watching for processes that start encrypting files, and stops them early.