Privacy policy
Last updated: November 13, 2026
Danna ("Danna", "we", "us") is an app that runs 28-day experiments on your own health data: for each experiment you run, it plans test days and normal days, asks you each day whether you did the experiment, and on the last day compares your sleep, heart or activity data on test days with normal days. This policy explains what we collect to do that, how we use it, who processes it for us, how long we keep it and how to delete it. It applies to the Danna Android app and the website at danna-xi.vercel.app (together, the "Service").
In short: Danna uses your health data only to run your experiments and show you your results. We never sell it, never use it for advertising, and never share it with data brokers. You can delete your account and all of its data at any time.
1. Information we collect
1.1 Account information
- Your email address and name.
- Your password, if you sign up with email. It is stored only as a secure hash by our authentication provider; we never see it.
- If you sign in with Google, we request only the basic email and profile scopes and receive your Google account ID, email address, name and profile picture URL. We do not access your Gmail, contacts, calendar, Drive or any other Google data.
1.2 Health and fitness data
Only after you connect a source and grant permission, Danna reads the following from it:
| Source | What Danna reads |
|---|---|
| Health Connect (Android) | Sleep sessions, heart rate variability, resting heart rate, heart rate, blood glucose, steps, active calories burned and exercise sessions, including history from before you connected; and body composition (weight and body fat). If you allow it, Danna also reads these in the background while the app is closed, only to tell you as soon as a day's result is ready (and whether that day looked clearly different from your usual) or when a habit pattern first has enough days. This happens on your phone; nothing new is sent anywhere. |
| Samsung Health | Sleep, heart rate, blood glucose, steps, daily activity (active time and calories) and body composition (weight, body fat, skeletal muscle and BMI). |
| Oura (if you connect it) | Your sleep periods (sleep time, deep sleep, heart rate variability and lowest heart rate), through Oura's API with your permission. |
| Dexcom (if you connect it) | Glucose readings, through Dexcom's API with your permission. |
| Apple Health (iPhone, if available) | Heart rate variability, resting heart rate and sleep stages. Danna never writes to Apple Health. |
Body composition is read on your phone only to show you your own latest numbers and an 8-week weekly trend on the Your data screen. It is never used to decide a verdict or choose an experiment, never stored on our servers and never sent anywhere.
You can also type in one thing yourself: each morning, Danna can ask how you feel today, and you tap a face from 1 (rough) to 5 (great). That answer is stored with your daily summary, is used only to compare your test days with your normal days, and you can leave it unanswered.
From those readings the app works out one summary per day: total and deep sleep minutes, heart rate variability, resting heart rate, steps, active minutes, active calories and the number of glucose spikes and, if you answer it, how you feel that morning (1 to 5), together with which source each number came from. Only these daily summaries are sent to and stored on our servers. The individual readings stay on your phone. The app's "Your data" screens, which show your latest raw readings, read them on your phone and do not upload them.
For Oura and Dexcom we also store the access tokens those services give us, so Danna can keep reading your data until you disconnect.
1.3 Your experiments
- The experiments you test, when each experiment started, and its plan of test days and normal days.
- Experiments you make yourself: the words you type for the experiment, when you do it, what it should change and whether it affects the next day. Only you can see them, and you can delete one until an experiment has used it.
- Your daily check-ins (whether you did the experiment that day, or that you chose to skip the day, which leaves it out of your verdict), anything you noted as unusual about the day (such as sick or travel), and your guess of how a day went before its result opened.
- What you want to find out first (sleep better, feel better, move more or not sure yet), chosen when you start, used only to suggest your first experiment.
- Your interests (up to three of Pets, Outdoors, Gym, Cooking, Reading and Music), if you pick them when you start or later. They are saved on your account and used only on your phone: they change how Danna and her cabin look, which cabin items and visitors you see first, and which suggestions are listed first. They never change a result, they are not shown to anyone else, and they are never sent to the AI.
- Your daily habits (up to three): which habit, its name if you type your own, when you do it, the days it repeats, helper steps and the days you marked it done. When you type your own habit, its name alone is sent once to our AI provider (see section 4) to choose how Danna acts it out in the app, and that choice is saved with the habit. Nothing else about you is sent with it.
- Your passport: an optional signature you draw with your finger in the app (saved as a drawing on your account), and how your profile picture looks (what Danna wears, a background colour, and whether to show your Google profile picture with a Danna badge or Danna alone).
- Your profile picture, if you take or choose one in Danna: a small square copy is stored to show on your Passport and to your friends and group members. You can change or remove it any time, and it is deleted with your account.
- Your verdicts: the comparison Danna calculated at the end of each experiment.
- Invites inside Danna: which group someone invited you to, who sent it, and whether you joined. When someone invites you by email, we look the email up only on our server, to show you the invite in the app; we never tell them whether it has an account, and we don't store the email.
- Groups, if you invite people to an experiment or join someone's: which group you are in, when you joined, and your profile picture link from Google, which we store only once you invite or join. You choose whether your result counts toward what the group found; it is off until you turn it on.
1.4 App interactions
When you tap one of the Danna Plus items for your cabin (the aquarium, string lights or wall art) without Plus, we save that tap: which item, your account and the time. We use it only to learn which items people want. It never includes health data, answers or results, it is not shown to anyone, it is not shared, and it is deleted with your account.
1.5 Information on your device only
- Your signed-in session, preferences and check-ins waiting to sync while you are offline.
- What Danna notices: which visiting animals you tap, your usual check-in time, interests suggested from the words in your habits, and what you chose to keep or turn off on that screen. It is kept only on your phone and never changes a result.
- Where Danna has traveled on her trip, the postcards you opened, and where you placed things in your cabin.
- Reminders. Danna schedules its notifications on your phone, and a background check on your phone announces a result once its data has arrived, a day that looked clearly different from your usual, or a new habit pattern.
- Friends' notifications. To deliver cheers, nudges and helper alerts, we store your phone's push notification token with your account, with your time zone and quiet hours. It is removed when you sign out or delete your account.
- Home-screen widgets (Android). If you add a Danna widget, it shows your selected friend group's name, its counts, your friends' first names and pictures, and the day's experiment question on your home screen, never health numbers or results. To draw it while Danna is closed, the phone keeps the selected group's name, counts and planet, and widgets refresh in the background with the same requests the app already makes. No new data leaves your phone. Removing the widget or signing out stops this.
1.6 What we do not collect
Danna does not collect your location, contacts, photos (other than a profile picture you choose), files, messages, advertising ID or browsing history, and does not include analytics, advertising or crash-reporting SDKs (the Plus item taps in 1.4 are saved by Danna itself, on our own database). Our hosting providers process technical information such as your IP address to deliver the Service and keep it secure.
2. How we use your information
- To create and secure your account and sign you in.
- To suggest experiments your data can actually measure.
- To plan your test days and normal days, record your check-ins, show your progress and calculate your verdicts.
- To remind you to check in, if you allow notifications.
- To learn which Plus cabin items people want, from the taps in 1.4 (counted, never used for advertising).
- To keep the Service working, secure and free of abuse, and to comply with the law.
We do not sell your personal information. We do not use it, or any health data, for advertising, marketing, credit or insurance decisions, or to build profiles for anyone else.
3. Health Connect, Samsung Health and Google data
Danna's use of information received from Health Connect adheres to the Health Connect Permissions policy, including the Limited Use requirements. In particular, data from Health Connect, Samsung Health, Oura, Dexcom and Apple Health is used only to provide Danna's features described in this policy; it is not transferred to third parties except the service providers below that run Danna for us, as necessary to provide those features, or as required by law; it is never used for advertising; and no person reads it except with your consent, for security purposes, or to comply with the law.
Danna's use and transfer to any other app of information received from Google APIs will adhere to the Google API Services User Data Policy, including the Limited Use requirements.
4. Who processes your information
Nobody else can see your data inside Danna unless you are in a group. Then the group's members see your name, your profile picture and how many days you have checked in, but never your answers, health data or own result. A group's combined result is shown only once at least 10 members have chosen to add theirs, never person by person. You can stop sharing your progress or leave a group at any time, and the group's host can remove you from it. People you have been in a group with can invite you again. There are no public profiles and no way to search or browse who uses Danna. We share information only with providers that run the Service for us, under their own privacy and security commitments:
- Supabase: authentication and database (your account, daily summaries, experiments, verdicts and the Plus item taps in 1.4).
- Vercel: hosting the website and the app's server.
- Anthropic, through Vercel AI Gateway: writes the plain-language explanation under a verdict, and picks how Danna acts out a habit you name yourself. For the explanation it receives only the verdict label, effect size, confidence, day counts, the experiment's name and your language; for a habit, only the habit's name. Never your name, email, raw readings or dates. The verdict label itself is always decided by Danna's fixed rules, never by AI.
- Google: Sign in with Google, if you use it.
- Oura and Dexcom: only if you connect them, to read your data from their services.
We may disclose information if required by law, to protect the rights and safety of our users or others, or as part of a merger or sale of the Service, in which case this policy continues to apply.
5. How long we keep it
- Your account, daily summaries, experiments and verdicts are kept while your account exists, so you can look back at past experiments.
- Disconnecting a source deletes its access tokens and stops Danna from reading it; daily summaries already saved stay until you delete them with your account.
- When you delete your account, all of it is deleted at once: account, daily summaries, connections and tokens, experiments, check-ins and verdicts. Copies in routine backups are removed as those backups expire, within 30 days.
6. Your choices and rights
- Delete your account in the app (Passport tab, then Account, then Delete account), or on the web at danna-xi.vercel.app/delete-account.
- Stop sharing a source by disconnecting it in Your data, or by removing Danna's access in Health Connect, Samsung Health, Oura, Dexcom or Apple Health.
- Notifications can be turned off in Settings or in your phone's settings.
- Google: remove Danna's access to your Google account at myaccount.google.com/permissions.
- Access or a copy of your data: email us and we will respond within 30 days. Depending on where you live you may have further rights, such as correction or objection; contact us to use them.
7. Security
Data is sent over encrypted HTTPS connections. Database access is restricted by row-level security so each account can reach only its own data, server keys are never shipped in the app, and access to personal data is limited to what is needed to run the Service. No method of transmission or storage is completely secure, but we work to protect your information.
8. Not medical advice
Danna is not a medical device. Its verdicts describe patterns in your own data and are not a diagnosis or a recommendation to start, stop or change any treatment. Talk to a doctor before changing anything that affects a medical condition.
9. Age
Danna is for people aged 18 and older. We do not knowingly collect information from anyone younger; if we learn that we have, we will delete it.
10. International transfers
Your information is processed in the United States, by us and the providers above, with safeguards appropriate to this policy.
11. Changes to this policy
We may update this policy. We will change the date at the top and, for significant changes, tell you in the app before they apply.
12. Contact
For any question or request about your privacy or your data, email dannyhilariosuarez@gmail.com. Danna is operated by Danny Hilario Suarez.