Privacy Policy
Cairn is built so that your data stays yours. The app runs entirely on your computer, and your backups go directly to the storage destination you configure. We have no servers in that path and never receive your files.
What we collect
Effectively nothing about you. Cairn has no account system and no analytics service that we use to track individuals. Your configuration — which folders you back up, which destinations you use, schedules, and credentials for those destinations — is stored only on your own computer.
| Data | Where it lives |
|---|---|
| Backup configuration (sources, schedules, destinations) | Locally on your device only. |
| Destination credentials (keys, passwords, tokens) | Stored securely on your device, or the cloud storage you control, and never transmitted to us. |
| Your repository password / encryption key | Held only by you. We never receive it and cannot recover it. Cloud storage providers only see encrypted data. |
| Application logs | On your device, for your own troubleshooting. You choose if you ever share them. |
Your files & your password
Before any backup leaves your machine, it is encrypted locally with AES-256 using a repository password that only you hold. Storage providers — and anyone else — only ever see scrambled data. Because the password never leaves your device, neither we nor your storage provider can decrypt your backups. If you lose the password, the data cannot be recovered; that is the intended security property, not an oversight.
Third-party storage you choose
When you connect a destination — an external drive, an S3-compatible bucket, an SFTP server, Google Drive, or OneDrive — your encrypted backups are sent there directly by the app. Those providers have their own privacy policies and terms that govern how they handle the (encrypted) data you store with them. We are not responsible for, and have no control over, third-party storage services. Sign-in authorizations for services like Google Drive and OneDrive are stored locally on your device.
Updates & telemetry
The app and its underlying Kopia engine can check for and download updates. These requests are limited to what's needed to deliver software updates and are not used to build a profile of you. Cairn does not sell data, show ads, or share information with advertisers.
Terms & Conditions
By downloading and using Cairn, you agree to these terms. They're intended to be fair and readable — please do read them.
License to use
Cairn is provided free of charge for personal, academic, and institutional use. You may install and run it on the computers you use. The app builds on the open-source Kopia engine and other open-source components, which remain governed by their own licenses.
Your responsibilities
- Keep your password safe. Your repository password is the only key to your encrypted backups. We cannot reset or recover it. Store it somewhere secure.
- Verify your backups. Leave verification enabled and periodically confirm you can restore. You are responsible for ensuring your backups meet your own needs.
- Use storage you're entitled to. You're responsible for the storage destinations you connect and for complying with their terms and any data-handling rules that apply to your work.
- Use the software lawfully. Don't use Cairn for anything unlawful or to back up data you don't have the right to store.
No warranty
The software is provided “as is”, without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose, and non-infringement. We do not guarantee that the software will be uninterrupted, error-free, or that any backup or restore will succeed in every circumstance. Always keep more than one copy of anything you cannot afford to lose.
Limitation of liability
To the fullest extent permitted by law, the authors and contributors of Cairn shall not be liable for any data loss or for any direct, indirect, incidental, special, or consequential damages arising out of the use of, or inability to use, the software — even if advised of the possibility of such damages.
Contact
Questions about privacy or these terms? Open an issue on the project's GitHub repository.