bKappa
Cross-platform incremental backup
...This means it cannot detect that a file has been renamed and makes full copies of renamed and partially modified files. It generates standalone restore scripts for the POSIX shell and PowerShell. While it saw real use, bKappa isn't tested enough to be your main backup software. If you are looking for that, BorgBackup and restic are good options as of 2024.
Warning! Old 1.x versions of bKappa are insecure. Do not use them. Because backup metadata is serialized with the "pickle" Python module (https://docs.python.org/2.7/library/pickle.html), a malicious backup can take over your machine.