Galaxy Watch on Android without Samsung Health
What I learned integrating Wear OS Health Services into FitMesh, and why Samsung Health was the wrong path.
When I started building FitMesh, the apparently easiest path was using Samsung Health as the data source. I figured out the catch early: Samsung Health doesn't expose a stable, public API for third parties to read raw data on Android. It existed, then it was deprecated, then it came back in a different shape, and today it's effectively a walled garden.
The right path: Wear OS Health Services
Health Services is Google's official API for biometric data on Wear OS. It works like this:
- You install a small client on the wearable (a Wear OS app)
- The client registers as a listener for the data you want:
HEART_RATE_BPM,STEPS_DAILY,CALORIES_DAILY, and so on - The data streams in while the user wears the watch
- Periodically, the client syncs it to the phone via the
Wearable Data Layer - On the Android phone, the FitMesh app receives it and forwards it to the backend
The traps I hit along the way
Battery drain. Initially I was sampling heart rate every 5 seconds. Result: a dead watch in 6 hours. I switched to MEASURE_TYPE_DAILY for aggregates and on-demand sampling only during an explicit workout.
Permissions. The user has to grant permissions on the phone and on the watch, separately. I had to design an experience that makes this two-step flow obvious without confusing anyone.
Offline-first. The watch isn't always connected to the phone. The Wear OS client writes to a local SQLite store, and the sync runs as soon as the Data Layer reconnects.
What I'd do differently
I would adopt androidx.health.connect.client as an additional layer: it lets you read data from other health apps too (Strava, Adidas, and so on), expanding the user base without writing custom integrations.
For now, the "Watch → Phone → Cloud" design works, but I have the feeling the right model is "Watch → Health Connect → Apps". We'll see if Google actually gets there.
Why Health Connect changes everything
androidx.health.connect.client is Google's unified health data hub, available as a system component on Android 14 and as a separate APK on Android 9–13. The concept is straightforward but powerful: any app can write biometric records into Health Connect, and any other app can read them — with explicit user consent for each data type.
For a project like FitMesh this means cleanly splitting two roles:
- Data collection: the Wear OS app continues to use Health Services to read the sensors, then writes the records into Health Connect via
HealthConnectClient.insertRecords. - Data reading: FitMesh — or any other app — requests read permissions and queries Health Connect, regardless of which wearable or companion app produced the data.
The practical outcome is that the integration stops being vendor-specific. A user with a Pixel Watch, a Galaxy Watch, or a Fitbit can feed the same data pipeline, as long as the relevant client writes to Health Connect. The wearable becomes interchangeable.
The trade-off worth keeping in mind: on Android 9–12, Health Connect requires a separate install from the Play Store, and the user may not have it. You need to handle the fallback with a clear message and a deep-link to the installation.
The "Watch → Health Connect → Apps" model isn't the de-facto standard yet, but it's Google's stated direction. Building toward it today reduces tomorrow's technical debt.