Privacy Policy

Last updated 14 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.
• Your own AI key, only if you connect one. Most people use Grethel's built-in coach and never do this. If you connect your own OpenAI or Anthropic key (an advanced option), it's stored encrypted, only ever decrypted on the server at the moment a request is made, never sent back to the app, never logged, and never stored in plain text — the app shows only its last four characters.

What we don't store

• Food photos. A photo you attach is sent to the AI model for the estimate and is not written to our database.
• Location, contacts, health data from Apple Health, or anything 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 instead connect your own OpenAI or Anthropic key, that data goes to your provider account under their terms rather than through us. Either way: 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.

We do not sell your data, and we do not share it with anyone else.

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, and your encrypted key — 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. Your provider key is encrypted at rest with AES-GCM and can only be decrypted inside our server functions.

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.

Contact

Questions, or a request about your data: support@grethel.app.