Kopia is an open-source backup and restore tool for selected files and directories. It encrypts snapshots before they leave your computer, deduplicates repeated data and applies compression and retention through policies. It is not synchronisation: a backup needs older recoverable snapshots.
KopiaUI or the command line?
KopiaUI is the friendly starting point on Windows, macOS and Linux. The official documentation says it can create/connect encrypted repositories, schedule snapshots, set compression and retention, restore data and run maintenance. The CLI gives server operators advanced controls; both use the same binary. Repositories can be local disks, mounted NAS paths, S3-compatible storage, Azure, B2, Google Cloud Storage, Google Drive, SFTP or WebDAV as currently documented. Provision and pay for storage yourself.
Create the first repository
Install from the official installation page. In KopiaUI choose Local Directory or NAS, select a destination and set a strong repository password. CLI users can follow the documented kopia repository create filesystem --path=PATH, then kopia snapshot create SOURCE flow. Replace PATH and SOURCE carefully: the repository destination will receive backup data.
Set a policy for scheduling, ignores, retention and optional compression. Read kopia policy show before assuming defaults fit. The project documents AES-based encryption by default and warns there is no recovery if you lose the repository password—store it and connection details in a password manager.
Do a genuine restore test
Create a harmless test file, snapshot it, then use KopiaUI’s restore to a separate empty folder or the documented kopia snapshot restore SNAPSHOT_ID DESTINATION command. Open and compare the restored file. You can also mount a snapshot to browse it, and kopia snapshot verify checks stored contents. Do not restore over the original path or prune old snapshots until you understand the target and retention consequences.
Storage, 3-2-1 and operational risks
For a computer, back up important folders to an encrypted external drive and keep another encrypted copy elsewhere. For a home server, snapshot application data using its consistent-backup method. The 3-2-1 principle means three copies, two media types and one off-site; Kopia does not automatically satisfy it. Run maintenance, watch failed jobs, read release notes before upgrades and test recovery after changes. Deduplication and compression save space, not data from a single lost repository.
FAQ
Does Kopia image my whole computer?
No. It snapshots the files and directories you select.
Is cloud storage included?
No. Storage accounts, buckets and costs remain yours.
Why restore-test?
A successful job proves data was written; a restore proves you can find, decrypt and use it.