Support

The Gearstack app for Apple Watch runs on watchOS 10 or later, which means Apple Watch Series 4 or newer, SE and Ultra. Which values arrive depends on what your model measures; the app reads them through Apple Health.

The app computes the analysis scores on your iPhone. To sync between your devices, health data is processed encrypted on EU servers in Frankfurt. The coach's cloud AI only receives data after your explicit consent, which you can withdraw in the app at any time. We do not sell health data.

The Apple Watch measures HRV optically at the wrist, mainly during quiet phases and at night. Single readings vary a lot from day to day. Gearstack compares each value with your own trend of the past weeks, and within the same source that trend is meaningful. Gearstack is preparing a chest strap that measures HRV more precisely; the waiting list is in the shop.

Yes. Your iPhone is enough to start: check-ins, training, nutrition and analysis run without an extra device. Values arrive automatically with an Apple Watch, with Fitbit or with any device whose app syncs with Apple Health.

Gearstack subscriptions are managed via the Apple App Store. Go to Settings → Apple ID → Subscriptions → Gearstack Health → Cancel. You keep access until the end of the billing period.