Privacy policy

The short version

Cairn needs no account and shows no ads. Health data stays on your device: Cairn never sends it to us, to iCloud, or to anyone else. Your habits and their history stay on your iPhone and iPad and, if you use iCloud sync, in your own private iCloud storage, which we cannot read. We do not sell data, and the app never asks to track you.

Apple Health

If you link a habit to Health, Cairn asks for that one type of data, at the moment you save the habit, and reads it on your device to mark the habit done. What it reads, such as steps, minutes or litres, is kept on your device only. When you log water, caffeine, a mindful session or tooth brushing in Cairn, it is also written to Health, and undoing the log removes it again. Settings, Health lists every habit that reads or writes Health.

Health data is never sent to us, never included in analytics or crash reports, never used for advertising or marketing, and never stored in iCloud by Cairn. For a Health habit, iCloud sync carries only whether each day was done, partly done or missed, so an iPad without Health can show your streak. Backups and exports never include Health values. You can change what Cairn may read or write at any time in the Health app, under Sharing, Apps.

iCloud sync

With iCloud sync on (Settings, iCloud), your habits and every log are stored in your own private iCloud database by Apple, so your devices stay in step. We cannot see or reach that database. Erase all data removes it from iCloud as well.

Analytics and crash reports

We use Google's Firebase Analytics to count how Cairn is used (for example how many habits are logged, which kind of habit, whether reminders are on) and Firebase Crashlytics to receive crash reports. These carry a random app instance identifier, device type and system version. They never carry your habits' names, your notes, anything you type, or any Health value: every event is a name and a few fixed words, and numbers are dropped before anything is sent. You can turn usage data off in Settings, About, Share anonymous usage data. Crash reports are always sent and contain no personal data.

Purchases

Cairn Unlock is sold by Apple. We learn only whether it is owned on your Apple Account, or shared with you through Family Sharing, to unlock it.

Reminders and widgets

Reminders are notifications scheduled on your device. Widgets read what the app saved on your device. Nothing about either is sent to us.

Children

Cairn is not directed at children under 13 and collects no information knowingly from them.

Your choices

Settings, Backups and export gives you all your data as a file at any time. Erase all data removes every habit and log from this device and, with sync on, from iCloud and your other devices. Deleting the app removes everything on the device.

Who we are

Cairn is made by Nubeo Studio, nubeostudio@gmail.com. This policy covers the Cairn app (Cairnday on the App Store) on iPhone and iPad, and is also at nubeostudio.com/cairn/privacy. Last updated 27 September 2026.