BorgBackup
A deduplicating backup tool, forked from Attic in 2015. Written in Python with performance-critical parts in C. The classic choice for backing up Linux servers to a machine you own.
The same core idea as restic — chunking, deduplication, compression and authenticated encryption — but with one important architectural difference: Borg wants to run its own binary on the far end too, over SSH. That makes transfers efficient because deduplication happens at the destination, but it means a plain S3 bucket can't be a target without help. Append-only mode is the strongest argument for it: a compromised client can then add new archives but not delete old ones, which protects the repository against ransomware. Borgmatic is the wrapper that adds declarative configuration and scheduling.