This policy covers Cairn, the self-hosted backup monitor, and Cairn for Android, both made by Low & Slow Studio (“we”).
The short version: you run Cairn yourself. The Android app is a client for your Cairn server. We don’t operate a Cairn service, so there is no server of ours for your data to go to, and we never receive it.
What the Android app sends, and where
- The app talks only to the Cairn server addresses you add, and, if you turn on instant alerts, to the Gotify server you enter. It doesn’t contact us or any third party.
- To those servers it sends your access token (or, if you sign in with a password, your username and password, once, to get a token) and the requests needed to show status and run the actions you tap.
- Addresses on your local network use plain HTTP on that network; public addresses use HTTPS.
- To help whoever runs that server fix problems, the app also tells that same server which screens you opened and which requests failed (with the server’s reference code for the failure). If the app crashes, it asks you once whether to send crash reports; only if you agree does it send them, again only to your own Cairn server. A crash report holds the app version, your phone model, the Android version and the technical trace, never anything about your backups. Nothing in this paragraph ever goes to us.
What stays on your phone
- Your server addresses, access tokens and the optional Gotify token, encrypted with a key held in the Android Keystore.
- The latest health summary (for the home-screen widget) and your settings.
- When you pair by scanning a code, the camera is used only to read that code. Images aren’t stored or sent.
- Notifications are created on the phone from your own server’s status or your Gotify messages.
- A rolling log of what the app did and what failed (two small files of at most 256 KB each). It’s never sent by itself; you can share it as a file from Settings → Share log, for example when asking for help.
Permissions
| Permission | Why |
|---|---|
| Internet, network and Wi-Fi state | To reach your Cairn server, and to tell your home network from elsewhere so the app can use the right address. |
| Wi-Fi multicast | To find a Cairn server on your local network automatically. |
| Notifications | To tell you when backup health gets worse. |
| Foreground service (remote messaging) | To keep the instant-alert connection to your Gotify server open, if you turn that on. |
| Run at startup | To resume background health checks after the phone restarts. |
The Cairn server
The server runs on your own hardware and keeps its data in a database on that machine. It sends alerts only where you configure it to: email, Gotify, or an uptime-kuma push monitor. It has no telemetry and doesn’t report to us.
It keeps a log of every change made through it (who did what and when, and what it changed), its background jobs and any failures, including the problem reports the app sends. Passwords and tokens are never recorded in it. The log is kept for 400 days (daily totals after that), stays on your server, and only its admin accounts can read it, on the server’s Log page. Updating it downloads the new version of the software; nothing about your installation is sent.
What Cairn doesn’t do
No accounts with us, no advertising, no analytics or tracking, no crash reports or problem reports to us (if you agree, crash reports go only to your own server), and no selling or sharing of data. The app requests no location, no contacts and no advertising ID.
Your control and deletion
See Delete your data.
Children
Cairn is a tool for people who run their own servers. It isn’t directed at children.
Changes
If this policy changes, we’ll update the date at the top.
Contact
Questions or requests: [email protected].