Our verdict: Kopia is a fast open-source backup tool for people who want encrypted, versioned file backups on storage they control. Snapshots are incremental and deduplicated, so frequent backups stay small. It backs up files and folders, not whole disks, and the settings assume some technical comfort.
About Kopia
Kopia is an open-source backup program under the Apache License 2.0. It saves snapshots of the folders you choose into a repository on a local or network drive, an SFTP or WebDAV server, or cloud storage such as Amazon S3, Azure, Backblaze B2 and Google Cloud Storage. Other cloud drives work through Rclone, which the project calls experimental. You pay the storage provider yourself; Kopia has no storage service of its own.
Everything is encrypted with AES-256 or ChaCha20 before it leaves your PC, and Kopia cannot create unencrypted backups. Only changed parts of files are uploaded, and identical files are stored once. KopiaUI is the desktop app for Windows; it bundles the same command-line engine, which offers some advanced features the GUI does not yet show.
What it does well
- Incremental snapshots. Each snapshot uploads only new or changed data, splitting large files into chunks.
- Deduplication. Identical files and moved or renamed files are stored only once.
- End-to-end encryption. AES-256 or ChaCha20 with a repository password that never leaves your machine.
- Policies. Schedules, exclusions, retention and compression per folder, user or machine.
- Flexible restore. Mount a snapshot as a drive, restore everything or pick single files.
Who it is for
Good fit
Users who want encrypted, versioned backups of their files to a NAS, external drive or their own cloud bucket.
Look elsewhere
People who need a full system image to restore Windows after a disk failure, or who want backup storage included.
Pros and cons
Pros
- Free and open source
- Client-side encryption is always on
- Fast incremental backups with deduplication
- Works with many storage types
Cons
- Backs up files only, not a bootable system image
- Some advanced features are only in the command line
- A lost repository password means lost backups
How to install Kopia
Run KopiaUI-Setup from the official GitHub release; winget install Kopia.KopiaUI also works. On first launch, create a repository and choose a strong password: Kopia cannot recover a forgotten password, and without it the backups cannot be read. Then add the folders to back up and set a schedule in the policy.
Questions about Kopia
Is Kopia free?
Yes. Kopia is open source under the Apache License 2.0. You only pay for the cloud storage you choose to use, if any.
Can Kopia back up to Google Drive or OneDrive?
Yes, through Rclone. The Kopia documentation calls Rclone support experimental and says it has been tested with Dropbox, OneDrive and Google Drive.
Does Kopia encrypt backups?
Always. Data and file names are encrypted on your PC before upload, and unencrypted repositories are not possible.
