Privacy Policy

GainCurve: Level Up Fitness · Effective 27 September 2026

Short version: GainCurve has no accounts, no analytics, no ads and no tracking. Everything you log stays on your iPhone and Apple Watch. The developer never receives your data.

Who is responsible

The controller is noubyte, the developer of GainCurve. The developer's name and postal address are shown on GainCurve's App Store page in the EU. Contact: noubyte@absan.de.

Data stored on your device

Workouts, sets, training plans, food logs, recipes, body measurements, goals and settings are stored locally on your iPhone (and workouts in progress on your Apple Watch). They are not uploaded to any server run by the developer and are not synced to iCloud by GainCurve. Your device backups (iCloud or computer) may include this data, as they do for any app. Deleting GainCurve deletes this data.

Apple Health

With your permission GainCurve reads steps, body weight, body fat, height, age (date of birth), sex, workouts (including their GPS routes), active energy, heart rate and food logged in other apps (calories, protein, carbs, fat, fibre, sugar) from Apple Health, and can save workouts to Apple Health. Health data is used only to show your progress, estimate and adapt your calorie target and measure cardio zones inside the app. It is never used for advertising, never sold and never shared with third parties. You can change or revoke access at any time in the Health app (Sharing → Apps → GainCurve).

If you choose an outdoor run, walk or ride on Apple Watch, GainCurve uses your location while that workout is running to record its route, and saves the route with the workout to Apple Health. Location is never used at any other time and never leaves your devices.

If you also use DayCurve, our caffeine and sleep-timing app, and switch the link on in both apps, DayCurve shares your recent caffeine doses, caffeine half-life, planned bedtime, limits, and its summary of your sleep (last night, your sleep need and sleep debt) with GainCurve, so GainCurve can show your caffeine level next to your workout and how last night's sleep reads for today's training. In return GainCurve shares your recent workouts (times, type and how hard), your usual training time and the time and calories of each day's last meal with DayCurve, so DayCurve can time caffeine and sleep advice around your training. This happens on your iPhone only, through storage shared by the two apps; nothing is uploaded, and you can switch it off in Settings at any time.

Apple Watch

The iPhone and Apple Watch apps exchange your routines, records and finished workouts directly with each other through Apple's WatchConnectivity and HealthKit. Nothing passes through the developer.

Food search and barcodes

When you search for a food or scan a barcode, the search text or barcode number is sent to the public food databases below to find matching products. No account, name, location or identifier about you is sent with these requests, but like any internet request they can see your IP address. Their own privacy policies apply:

The 15,000 built-in foods are searched on your device without any network request.

Recipe import

If you share a recipe web page to GainCurve, the app downloads that page to read its ingredients. Only the address you shared is contacted.

Camera, progress photos and notifications

The camera is used to read barcodes and, if you use GainCurve Pro, to take progress photos. Progress photos are stored only inside GainCurve on your iPhone with iOS's strongest file protection, never added to your photo library, never uploaded and never synced to iCloud by GainCurve (encrypted device backups include them). You can delete them one by one or all at once in Settings, and optionally lock them with Face ID; GainCurve never receives your face data. Notifications (rest timer, interval alerts, optional training reminders) are created and delivered on your device.

In-app purchases

GainCurve Pro is sold through Apple's App Store. Apple handles payment and your Apple ID; GainCurve only asks the App Store on your device whether Pro is active and receives no payment or account details. See Apple's privacy policy for how Apple processes purchases.

Legal basis (GDPR)

Processing happens on your device at your request to provide the app's features (Art. 6(1)(b) GDPR); Apple Health data is only accessed with your explicit consent (Art. 9(2)(a) GDPR), which you can withdraw in the Health app at any time. Because the developer does not receive your data, requests for access or deletion can be fulfilled by you directly in the app or by deleting it. You have the right to lodge a complaint with a data protection supervisory authority.

Children

GainCurve is not directed at children under 13 and does not knowingly collect data from them.

Changes

If this policy changes, the new version will be posted on this page with a new effective date.