Privacy Policy — Body Composition Tracker
Last updated: August 3, 2026
This policy describes how Johannes Rukaber / JRDevDesign (“we”, “us”) handles information when you use the Body Composition Tracker application on Android, iOS, and the web. The app helps you record body composition measurements (for example weight and body fat estimates), optional progress photos, and goals. Data you enter is stored locally on your device; measurement content is not uploaded to our servers.
Related pages: Support · Health disclaimer · Imprint (Impressum)
1. Controller
Johannes Rukaber, jrdevdesign
Adam-Stegerwald-Str. 20, 63811 Stockstadt, Germany
Email: johannes@jrdevdesign.com
Where the GDPR applies, this is the controller under Art. 4 No. 7 GDPR.
2. Data stored on your device
The app processes only data you enter or choose to attach, including:
- Health and fitness entries: weight, body fat percentage, calculation method, optional age, biological sex, skinfold measurements, notes, and goals
- Optional progress photos (camera or photo library), stored as files in app storage
- App preferences (for example language, theme, units)
- Technical integrity metadata and backup-related secrets in the device secure store
Measurement data is stored locally (for example via on-device storage APIs). We do not receive a copy of your body composition entries or photos simply because you use the app.
3. No accounts
Body Composition Tracker does not require a user account and does not provide cloud sync of your measurements to us. Deleting data is done in the app (for example “delete all entries”) or by uninstalling the app.
4. Camera and photos
If you attach progress photos, the app may request access to your camera and/or photo library / media images. Access is used only for features you initiate. Photos stay on your device and are not included in encrypted backup exports.
5. Backups, CSV export, and sharing
Optional backups create an encrypted archive locally (XSalsa20-Poly1305 via TweetNaCl). CSV export and the system share sheet let you share files you choose. You decide whether and how to share those files with others or with cloud services you control. We do not automatically upload backups to our servers.
6. App updates (Expo / EAS Update)
The mobile app may download over-the-air updates (for example JavaScript bundles) from Expo infrastructure to deliver fixes and improvements. That can involve standard technical data such as app version and update status, as described in Expo’s privacy notice. This does not transmit your measurement journal content to us.
7. Google Play and platform services
When you download or update the app via Google Play (or other app stores), those platforms process data under their own policies (for example installation, device compatibility, and store account data). We do not receive your Play payment card details through this app; the current mobile app does not offer in-app purchases.
8. Analytics, ads, and crash reporting
The mobile app does not include advertising SDKs and does not operate a first-party analytics or crash product that sends your measurement content to us. If we add such tools later, we will update this policy and the Play Console Data safety form.
The separate marketing website for the product may use hosting and optional analytics under that site’s own notices.
9. Legal basis and retention (where GDPR applies)
Processing of data you enter is based on your consent (Art. 6 para. 1 lit. a GDPR) by actively using the app. You may withdraw consent by deleting data in the app. Data remains on your device until you delete it or uninstall the app.
10. Your rights
Because data is stored on your device, you can view, correct, or delete it in the app (including Art. 15, 16, and 17 GDPR where applicable). CSV export supports data portability (Art. 20 GDPR). You may lodge a complaint with a supervisory authority; for the provider in Germany that is typically the Hessian Commissioner for Data Protection and Freedom of Information (HBDI), P.O. Box 3163, 65021 Wiesbaden, Germany.
11. Children
The app is not directed at children under 13. We do not knowingly collect personal information from children under 13. If you believe a child has provided us information, contact us and we will take appropriate steps.
12. Security
We use commercially reasonable measures for the services we operate. Local backups use encryption as described above. No method of electronic storage is completely secure; you remain responsible for physical access to your device and for any files you export or share.
13. Changes
We may update this policy from time to time. The “Last updated” date at the top will change when we do. Continued use of the app after changes means you accept the updated policy, except where applicable law requires additional steps.
14. Contact
Questions about this policy: johannes@jrdevdesign.com