Track your body. Nothing else.
Cairn logs weight, body composition and heart rate straight into Android Health Connect, and reads your watch's own steps, sleep and activity back for context. No account, no analytics, no network calls — it never leaves your two devices.
Cairn is in closed testing — sign up on the Play Store page above to get access.
What it tracks
Weight, BMI & body composition
Log a weigh-in and see BMI, body fat % and body water % trend over time.
Quick-log from your wrist
Add a measurement from the Wear OS app without reaching for your phone.
Continuous heart rate
Optional, watch-driven monitoring with today's min/avg/max and a full readings graph — on by choice, off by default.
Sleep, steps & calories, for context
Cairn reads — never writes — the sleep, steps and activity data your watch already recorded.
Full history
Every past measurement and heart-rate session, at a glance.
Metric or Imperial
kg and cm, or lb and ft/in — whichever you think in.
Built on Health Connect, not a server
Everything Cairn reads or writes lives in Android Health Connect, on your device. There's no account to create and no cloud to sync to, so there's nothing about you for a server to hold in the first place.