Last updated: February 2026
This Privacy Policy describes how your information is collected, used and disclosed when you use Tantal, and tells you about your privacy rights.
Responsible: Maximilian Stelzl, Limmatauweg 4, 5408 Ennetbaden, Switzerland
Contact: info@tantal.app
Account Data: Email address and password when you register. Authentication is handled via JWT tokens.
Profile Information: Name, age, height, weight, gender, activity level, and dietary preferences — used to calculate your calorie target and personalize coaching.
Meal Data: Meals you log (text descriptions, calorie estimates, photos). Photos are processed for food analysis and not stored permanently on our servers.
Weight Entries: Weight measurements you record over time to track progress.
Workout Data: Exercise type, duration, and intensity you log.
Chat Messages: Your conversations with the AI coach (Ta), including onboarding and coaching sessions.
Voice Messages: Audio you send is transcribed using OpenAI Whisper and then deleted. We store only the text transcription.
Health Data (Apple HealthKit): With your permission, we read step count, active energy, and workout data from Apple Health. This data is used solely for coaching and is never sold or shared for advertising.
Location Data: With your permission, approximate location is used for context-aware coaching (e.g., restaurant detection). Location data is not stored permanently.
Calendar Data: With your permission, calendar events are read to help schedule meals and workouts. Events are not stored on our servers.
Accountability Partners: Phone numbers of contacts you add voluntarily. Used only to send nudge messages via SMS or WhatsApp when you request it.
Push Notification Tokens: If you enable notifications, we store device tokens to send coaching messages and reminders.
We use the following services to provide the app's functionality:
For EEA/UK users, our legal basis for processing is:
Your data is stored on a self-hosted server in Switzerland. All data transmission is encrypted via HTTPS. The database is encrypted at rest.
Your account data is kept as long as you use the app. Chat history, meal logs, and weight entries are retained to provide continuous coaching context. You can request deletion of all your data at any time.
Under GDPR/Swiss law, you have the right to:
To exercise these rights, email info@tantal.app
Tantal complies with Apple's HealthKit guidelines. Health data accessed through HealthKit is:
If you choose to participate in the optional commitment contract, your deposit amount and goal are stored. Deposits are handled through a regulated payment provider. Funds are either returned to you or donated to your chosen charity based on goal completion.
Tantal is not intended for children under 16. We do not knowingly collect personal information from children under 16.
Under the California Consumer Privacy Act, you have the right to:
We may update this Privacy Policy. Changes will be posted here with an updated date.
Questions? Email info@tantal.app