Privacy Policy

Last updated: 23 August 2026

1. Overview

JYL Balance ("the Application") is a free app for tracking weight, calories, macronutrients and hydration. This privacy policy explains how we handle your data.

Key point: JYL Balance stores the data you enter locally on your device. A few optional features you turn on yourself send limited data to external services, see sections 8 to 11. We never sell your data or use it for advertising.

2. Data Collection

For your core tracking data, JYL Balance works offline and collects nothing on our servers.

The Application operates entirely offline. The data you enter (weight, calories, macronutrients, hydration, personal notes) is stored exclusively on your device, in the browser or native app. This data is never sent to our servers.

Weight and weigh-ins
Meals and foods consumed
Personal goals
Preferences (language, theme, units)
Notes and comments

3. Data Storage

All your data is stored locally:

Web version: in your browser's localStorage (IndexedDB)
Mobile version: in your device's local app storage (private documents)

No cloud sync, no remote servers, no centralized backup. Only you can access your data.

4. Cookies and Trackers

JYL Balance does not use tracking cookies, analytics cookies, or third-party scripts to collect data about your behavior. We do not use Google Analytics, Mixpanel, or any other tracking platform.

Only strictly necessary cookies for technical operation may be used (e.g., for session management).

5. Food databases and community database

The Application includes a reference nutrition database (CIQUAL, source ANSES), usable offline. For packaged products, it may query the global community database Open Food Facts, handled according to its own privacy policy.

For technical reasons (CORS), these requests to Open Food Facts pass through a relay hosted on our server. Only the strictly necessary query is transmitted (product name or barcode); no personal data about you is sent, and these requests are not retained.

Community product database. When you scan a product missing from the existing databases, the Application may add it to a product database shared between users, to enrich the service for everyone. Only product data is stored there (barcode, name, nutritional values per 100 g), never personal data, nor any identifier relating to you.

6. Report for your Doctor (PDF)

The Application lets you generate a PDF report to present to a healthcare professional. Before generating it, a screen lets you enter a first and last name to personalize the document.

This name is never stored. It is kept only in memory, for the time needed to produce the PDF, then erased (in particular when the Application is reloaded). It is neither written to local storage nor transmitted to any server. The report is generated locally on your device; you alone decide whether to share it with your doctor.

7. Health data (Health Connect / Apple Health)

The Application offers an optional feature to sync health data via Health Connect (Android) or Apple Health (iOS). You enable it yourself in the settings; it is off by default. When enabled, the Application reads, read-only, the following data:

your steps;
your active calories (energy burned through physical activity);
your weigh-ins (weight), over the last 30 days;
your body fat, when provided by an impedance scale.
your sleep nights (duration and stages), when a compatible device provides them.

Strictly local use. This data is used only to display your daily activity, to add the calories burned to your energy expenditure estimate, and to automatically import your weigh-ins (weight and body fat) into your log to avoid double entry. It stays stored locally on your device, is never sent to our servers or any third party, and the Application never writes or modifies any data in Health Connect or Apple Health. You can revoke this access at any time in Health Connect / Apple Health or by turning the option off in the Application's settings.

Community challenges. As an exception to the above, when the optional "Community challenges" feature is active, the App sends our server, in an anonymous and aggregated form, simple daily totals — number of logged meals, glasses or litres of water, weigh-ins, steps (only if health sync is enabled) — linked to an anonymous device identifier. These totals are used solely to compute a shared collective goal for all users; they are not linked to your identity, enable no individual ranking, and no raw data (step history, weight, etc.) is transmitted. You can stop contributing by turning the feature off.

8. Meal scan (AI), sending a photo to an external service

The App offers an optional meal scan feature: you photograph a meal and an artificial intelligence estimates the foods, calories and macronutrients. This feature is disabled by default and is only enabled when you enter your own API key.

The photo leaves your device. Unlike your other data (which stays local), the photo you choose to analyze is sent, through our technical relay (scan.jyl-balance.com), to the AI provider you configured (e.g. Google Gemini or OpenAI), solely to produce the estimate. It is not retained on our servers (storage-free relay); its processing by the provider is governed by that provider's terms and privacy policy. Your API key is sent with each request and is never stored on our servers; it stays saved locally on your device.

Voice meal logging. The App also offers an optional (Pro) voice-logging feature: you dictate your meal into the microphone. Speech recognition is handled by your device's system, on Android the transcription is done locally, on iOS Apple may process the audio through its speech-recognition service (governed by Apple's privacy policy). In all cases, only the transcribed text, never the audio recording, is then sent via our technical relay (scan.jyl-balance.com) to the AI provider to estimate foods and calories. The audio is not stored on our servers. This feature is disabled by default.

Use this feature only for meal photos and avoid including people or sensitive information. You can stop using it at any time by removing your API key in settings. The values shown are estimates to be checked.

9. Premium subscription (RevenueCat)

The optional Premium subscription is managed through RevenueCat, a third-party provider. To activate your subscription, restore your purchases and prevent fraud, RevenueCat processes your purchase history and an anonymous subscriber identifier. No name or email address is required. This data is used only to manage your subscription and is governed by RevenueCat's privacy policy.

10. Remarks / feature requests

The app's settings include an optional form to send us remarks or feature requests (available in the mobile apps). If you use it, your message, and your email address only if you choose to provide one, is sent to and stored on our server so that we can read it and, if needed, reply. The email is optional; without it you can still send your message. This data is never sold or shared for advertising.

11. Referral

The optional referral feature lets you invite friends. If you take part, an anonymous identifier generated by the app for your device is sent to our server, solely to attribute referrals and prevent abuse. It is not linked to your identity and is only sent if you use this feature.

12. User Rights (GDPR)

You have the following rights over your data:

Access: You can access all your stored data via the "Export" function in the Application.
Deletion: You can delete your data at any time directly from the Application or by clearing your browser/device local storage.
Portability: You can export your data in JSON format for use elsewhere.
Correction: You can edit or correct your data directly in the Application.

13. Technical Data

JYL Balance may receive minimal technical information from the web server hosting it, such as IP address or browser type (standard server logs). This information:

Is not processed personally
Is used only to maintain server security and stability
Is deleted according to the hosting server's retention policy

14. External Links

The Application may contain links to other sites or services (Open Food Facts, Play Store, etc.). We are not responsible for their privacy policies.

15. Security

Since all your data is stored locally, security depends entirely on your device. We recommend:

Securing your device with a password or biometric authentication
Keeping your operating system up to date
Making regular backups (via the Export function)

16. Policy Changes

We may update this policy from time to time. Changes will be posted on this page with an updated "Last updated" date. Continued use of the Application after changes constitutes your acceptance.

17. Contact

For any questions about this privacy policy or your data:

contact@jyl-balance.com

18. GDPR Compliance

JYL Balance complies with the General Data Protection Regulation (GDPR) because:

No personal data is collected without explicit consent
You maintain full control of your data
Data is shared with third parties only for optional features you enable (see §8-11), never for advertising
You can delete your data at any time