Kopia

Deduplicating encrypted snapshots with retention policies, a CLI and a GUI that share one repository format.

What it does

Kopia snapshots directories into a repository on object storage, SFTP, WebDAV, a local disk or Backblaze B2, with per-path retention policies, compression and client-side encryption. KopiaUI is the desktop front end over the same repositories, so a machine can be driven by whichever fits.

kopia repository create filesystem --path /Volumes/Backup/kopia
kopia policy set --global --keep-daily 30 --keep-monthly 12
kopia snapshot create ~/Documents
kopia snapshot list

Notes

Retention is declarative — a policy per path, inherited from a global default — rather than something you script around forget.
The formula installs the CLI only. KopiaUI ships as a separate download from the releases page.

Alternative to

Alternative	Type	Trade-off
restic	Open source	More mature and more widely audited; no GUI, no policy engine
BorgBackup	Open source	Longer track record, but cannot write to object storage
Arq	Paid	Commercial support and a Mac-native interface
Duplicati	Open source	Similar scope, web UI, slower and more fragile