Cairn: Health Aggregator

Cairn reads your health and fitness data from the phone's health store — Apple

Health on iOS, Health Connect on Android — and saves it as plain, open-format

files (Open mHealth / IEEE 1752.1 JSON) in your own Nextcloud. You stay the sole

owner of your data: there is no central server and the developer stores nothing.

Requirements:

* Android 14 or newer. Cairn reads through Health Connect, which is part of the

system only from Android 14; on Android 8-13 it is a separate Google app from

the Play Store, which a Play-less device cannot install — so the app would

find nothing to read.

* A Nextcloud of your own is optional: without one, Cairn still reads and shows

your data, it just keeps the files on the phone.

Features:

* Reads heart rate, steps, body weight, sleep and workouts — read-only. Cairn

never writes to your health store.

* Syncs the files to your own Nextcloud over WebDAV, with optional background

sync.

* In-app dashboard with a sleep-stage deep-dive and a BMI computed from your

latest weight.

* Available in English and German.

Privacy:

* No advertising, no analytics, no trackers, no third-party services.

* Your data lives only on your device and in the Nextcloud you control — never

in any developer or third-party cloud.

* HTTPS only. The Nextcloud app password is stored in the operating system's

secure storage and can be revoked at any time.