Your location, for the few you trust.

• No accounts. Your identity is a key generated on your device — no email, phone or password.
• End-to-end encrypted. Your location, and even your name, are encrypted on your device and readable only by the people you pair with.
• You choose how precise. Share your exact position, a rough area (about 1 km), or nothing, separately for each person.
• Self-hostable. Point the app at your own server and your data never leaves it.

More detail: how the encryption works and what the server can see.

Cairn only shares while the app is open, unless you turn on Share in the background. That's off until you choose it.

• When you turn it on, Cairn first explains what it does, then Android asks you to allow location "all the time".
• It keeps sharing your location with the contacts you've paired with, even when the app is closed.
• A notification stays on screen the whole time it's running, so you always know.
• Your location stays end-to-end encrypted, and you can turn it off at any time.

• Pairing needs the other person. Someone can only connect with you if you show them your QR code in person, or send them a one-time invite code that expires after 24 hours.
• You're told about new connections. By default, Cairn notifies you when someone new connects with you.
• It's visible. Background sharing always shows a notification, and every person you share with is listed in the app.
• Stopping is one tap. Pause sharing with anyone, or remove them entirely, whenever you like.

• Not an emergency service. In an emergency, call 999 (or your local number).
• Not for tracking people without their consent. Everyone you see on the map chose to share with you.
• Not real-time to the second. To save battery and avoid revealing when you move, it updates on a steady schedule: every 30 seconds while the app is open, and every few minutes in the background.