Privacy Policy
Last updated 31 July 2026
Grethel is a health-coaching app. To do its job it holds some genuinely personal information — what you eat, what you weigh — so this page says plainly what is stored, who else sees it, and how to erase it. There is no advertising, no analytics, and no tracking of any kind in Grethel.
What we store
- Your account. Your email address, and a password that is stored only as a salted hash.
- Your body stats and goal. Age, sex, height, weight, your goal and target rate, and your preferred units. These are what the calorie formula runs on.
- What you log. Meals (your description plus the estimated calories and macros), activity, weigh-ins, water, and any meals you save as favorites.
- Your conversation with Grethel, so the thread is still there tomorrow.
- Food photos you attach, for 7 days. A photo you send with a meal is kept in a private store — readable only by your account — so the meal card can show it. After 7 days it's deleted automatically. It's also sent to the AI model for the estimate (see below).
- A push token, only if you opt into feature updates. If you turn on the "feature updates" notification in the app, we store the device token Apple or Google issues so we can deliver those notifications. It exists only while that setting is on: turn it off and every token for your account is deleted. Reminder notifications (food and water) are scheduled on your phone by the app itself — they involve no token and nothing stored on our servers beyond the times you chose.
What we don't store
- Location, contacts, health data from Apple Health, or anything else from your device we didn't list above.
- Analytics, advertising identifiers, or any third-party tracking SDK. Grethel contains none.
Who else sees your data
The AI model behind the coach. By default, Grethel's coach runs on a model we host through OpenRouter (currently Mistral). When you send a message, the model receives your message, any photo you attached, and the context Grethel assembles to coach you: your body stats, your targets, and your recent logs. It's used to generate the reply, not to train the model. If you'd rather the model didn't see something, don't put it in a message.
Supabase hosts the database and handles sign-in on our behalf. They process your data only to run the service.
Notification delivery, only if you opt in. If you turn on feature-update notifications, your push token and the notification content pass through Expo's push service and Apple's (APNs) or Google's (FCM) notification systems — that is how any app's push notifications are delivered. They process this only to deliver the notification.
We do not sell your data, and we do not share it with anyone else.
Where your data is processed. Grethel's providers — Supabase, OpenRouter, and (if you opt into feature updates) Expo, Apple, and Google — may process and store data on servers outside the European Economic Area, including in the United States. Where that happens, the transfer is covered by the European Commission's Standard Contractual Clauses (or an equivalent safeguard) in our agreements with them.
Your rights
If you're in the EU or UK, the GDPR gives you rights over your personal data, and Grethel supports them directly:
- Access and portability. Open Settings → Export my data to download everything we hold about you as a ZIP of spreadsheets — your profile, logs, chat, and more — in a structured, machine-readable form you can take elsewhere.
- Rectification. Edit your profile, goal, and any meal or weigh-in in the app at any time.
- Erasure. Open Settings → Delete account to erase everything, immediately and permanently (see below).
- Restriction, objection, and withdrawing consent. You can stop processing at any time by deleting your account. For anything more specific, email us.
- Complaint. You have the right to lodge a complaint with your local data protection authority.
Why we're allowed to process this (legal basis)
The meals, weight, and body stats you log are health-related information — a "special category" under the GDPR. We process it on the basis of your explicit consent, which you give by checking the consent box when you create your account, and which you can withdraw at any time by deleting your account. We process your account details (email, password) to provide the service you asked for — the basis is performance of our agreement with you. Feature-update notifications are also based on your consent: they're off until you turn them on, and turning them off withdraws that consent and deletes your push token. We rely on no other basis, and we do not use your data for advertising or profiling.
How long we keep it
We keep your data for as long as your account exists, so the app can coach you over time. Food photos are the exception — they're deleted after 7 days — and push tokens are deleted the moment you turn feature updates off, when you sign out on a device, or with your account. When you delete your account, everything goes at once, with no backup copy kept for you.
Deleting everything
Open Settings → Delete account in the app. That erases your account and everything attached to it — profile, meals, weigh-ins, water, favorites, chat history, food photos, and any push tokens — immediately and permanently. There is no recovery, and we keep no backup copy for you. You can also delete individual meals and weigh-ins at any time without deleting the account.
Security
Traffic is encrypted in transit. Your rows are readable only by your own account, enforced by the database itself.
Children
Grethel is not intended for children under 13, and we don't knowingly collect their information. Because it deals with calorie targets and weight, we don't think it's appropriate for children at all.
Changes
If this policy changes in a way that matters, we'll update the date at the top and note the change in the app before it takes effect.
Who's responsible for your data
The data controller for Grethel is Grethel, operated by Andres Gracia, 45 E City Ave #467, Bala Cynwyd, PA 19004, United States. For any question or a request about your data — access, correction, deletion, or a complaint — contact grethel.app@gmail.com and we'll respond within 30 days.