Effective date: November 9, 2026 | Last updated: October 26, 2026 | Previous version: effective October 21, 2026
This policy explains what information Stackd collects, how we use it, who we share it with, and the choices you have. We wrote it to be read, not skimmed past. If anything is unclear, email support@stackd.health.
Stackd is a mobile app and website (stackd.health) operated by Stackd Health LLC, a Massachusetts limited liability company ("Stackd", "we", "us"). We are responsible for your personal information as described in this policy.
Contact: support@stackd.health
This policy covers the Stackd iOS app, the stackd.health website, and any support conversations you have with us.
If you turn on Apple Health access, Stackd can read the data types you approve, which may include steps, heart rate, resting heart rate, heart rate variability, blood oxygen, respiratory rate, sleep, active energy, and body weight. Stackd does not read your workouts from Apple Health. If you tap Fetch from Apple Health on a cardio exercise during a workout, Stackd reads your average heart rate from Apple Health and saves it with that workout on our servers. Body weights imported from Apple Health are saved to your weight log (see Section 5). After you record an activity with Cardio, Stackd reads your heart rate from Apple Health for that activity's time, if you have allowed heart rate access, and saves its average with the activity. Stackd can write workouts you complete in Stackd to Apple Health if you turn that on when saving a workout, and, for an activity you record with Cardio, its route if you allow it. You can change or revoke this at any time in the iOS Settings app under Health, Data Access and Devices.
Stackd does not include advertising SDKs or third-party analytics SDKs, and we do not track you across other companies' apps or websites. Crash reports are never used for advertising or tracking.
Subscriptions are sold and billed by Apple. We receive your subscription status (for example, active, trial, or expired) through Apple and our subscription provider RevenueCat. We never receive your payment card details. If you install Stackd from one of our ads on the App Store (Apple Ads, formerly Apple Search Ads), Apple shares which ad campaign the install came from, and RevenueCat records it with your subscription so we can measure our ad results; it is not used to track you across other apps, and it is not sold.
Cardio, a Premium feature, records runs, walks, hikes, rucks and rides. Only while you record one, from the moment you tap Start until you tap Finish, Stackd uses your iPhone's precise location, including while your screen is locked or Stackd is in the background. iOS asks for your permission the first time you tap Start, and shows a location indicator whenever Stackd is using your location. Stackd also uses your iPhone's motion sensors, with your permission, to count your steps and measure your climb while you record.
We use your location to draw your route and to measure distance, pace, elevation, laps and loops. While you record, your route is kept on your iPhone. When you save the activity, it is stored with your account in private storage (see Section 8) and shown only to you. It leaves Stackd only if you choose: in a card you share (see Section 7), or as a workout route you let Stackd save to Apple Health (see Section 3.2).
Stackd does not use your location at any other time and does not use it to track you. We never sell it, never use it for advertising, and never send it to Anthropic or any AI feature. Indoor run works without location. You can turn location off for Stackd at any time in the iOS Settings app, under Privacy & Security, Location Services.
We do not sell your personal information. We do not use your health information for advertising, and we do not share it with advertisers or data brokers.
Stackd's AI features are powered by Claude, a model provided by Anthropic, PBC. AI features only run after you give consent in the app, and you can withdraw that consent at any time in Settings. If you withdraw consent, AI features stop working, and the rest of the app keeps working.
What we send to Anthropic when you use an AI feature, limited to what that feature needs:
Apple Health data. Stackd does not send Apple Health data to Anthropic as it reads it. The one exception is body weight: if you allow weight access, weights Stackd imports from Apple Health are saved to your weight log and profile, and like a weight you enter yourself, your current weight can be included with your health profile in AI requests and your weight trend in monthly reports. Steps, heart rate, resting heart rate, heart rate variability, blood oxygen, respiratory rate, sleep, and active energy from Apple Health are never sent to Anthropic.
What we never send: your name, email address, password, or payment information, your location, or the routes you record. An activity you record with Cardio reaches an AI feature only the way any workout does: its type, time, distance and calories.
Under Anthropic's commercial terms, information sent through its API is not used to train its models. Anthropic may keep API data for a limited time for safety and abuse monitoring, as described in its own policies.
AI output can be wrong. See our Medical Disclaimer.
To look up nutrition facts, supplement labels, exercise information, and published research, Stackd queries these public databases. None of them receives your name, email address, or account:
Links to other websites. Buy on Amazon opens Amazon's website or app with a search for that product. Amazon then receives what any website receives from a visitor, such as your network address, and nothing else from Stackd. These are affiliate links: as an Amazon Associate, Stackd earns from qualifying purchases. A source you open from a Sources row loads the publisher's page in a browser in the same way.
Apart from what you choose to share with your friends (below), we share information only with service providers who help us run Stackd, and only as needed for them to do that job:
| Provider | Purpose |
|---|---|
| Supabase | Database, authentication, file storage, and server functions (United States) |
| Anthropic | AI features, as described in Section 5 |
| Apple | App distribution, Sign in with Apple, subscriptions, Apple Health, push notifications, and Apple Maps, which draws the maps in Cardio and receives the map area being shown, not your Stackd account |
| RevenueCat | Subscription status and entitlement management, and which Apple Ads campaign an install came from |
| Expo | App updates and push notification delivery |
| Sentry (Functional Software, Inc.) | Crash and performance diagnostics: crash stack traces, device model, iOS version, and app version, with no name, email, health, food, or lab data, used only to fix bugs (United States) |
| Optional Google sign-in | |
| Google Workspace (Google LLC) | Sends our account emails, such as sign up confirmation and password reset, from support@stackd.health, so it processes your email address; also receives the messages you send to support@stackd.health |
| Netlify | Hosts the stackd.health website, including the email confirmation and password reset pages, and receives your network address when you open them |
Sharing to Instagram, Messages, and other apps. When you tap a share button, the image you created is handed to the app you choose, such as Instagram, through iOS. Stackd uses a Meta App ID only so Instagram can open its Stories editor. Stackd does not send your account, health data, or any other information to Meta. Photos you pick as a share background stay on your device and are never uploaded to us. A card you share from Cardio shows the route of that activity on a map, so share it only where you are comfortable showing where you went.
Friends is optional. People you accept as friends see your username, your first name, and your profile photo, never your email. They see nothing else unless you turn it on.
Your profile photo is shown only to people you have accepted as friends. If you send someone a friend request, they see your username and first name with it, and your first initial in place of your photo. Anyone else who finds you by your exact username or a friend link sees only your username and first name, never your photo. If your first name does not pass our filter for objectionable words, your username is shown in its place. Your photo is never public: we store it privately, and Stackd shows a friend a copy through a link that expires within an hour. Someone you block, and someone who blocks you, sees none of it.
Every other item starts at Only me. For each one, you choose who can see it: only you, your close friends, or all your friends. You choose your close friends yourself, one friend at a time. The items are:
Before your peptides, hormones or weight trend are first shared, Stackd shows you the names of the people who will see them.
Never shared with friends, with no setting to share them: your medications, your lab results and bloodwork, and your health conditions. Our servers enforce this, not only the app: friends never read your data directly, and the server function that answers a friend returns only the items you share with that person.
A friend can copy a supplement, peptide or hormone you share into their own stack. The dose and schedule come with it only if you share them. What a friend copies becomes part of their own account.
You can remove a friend or block someone at any time. They stop seeing anything you share straight away and are not told. You can report a user: reports go to us for review, and the person reported is not told who sent it.
We may also disclose information if required by law, to protect the safety of any person, or as part of a business transfer, in which case this policy will continue to apply to your information.
Your data is stored with Supabase in the United States. We protect it with encryption in transit (HTTPS), hashed passwords, access controls that isolate each account's data (row-level security), and private storage for uploaded files and the routes you record. No system is perfectly secure, but we work to protect your information and will notify you of a breach as required by law.
On your phone. Stackd also keeps some of your data on your phone: the app's saved data, and the numbers the Home Screen widget shows. This data is excluded from iCloud and device backups, and the widget's numbers can be read only while your phone is unlocked. While you record with Cardio, the route is also kept on your phone until you save or discard the activity, excluded from backups in the same way, and your Lock Screen and Dynamic Island show the activity, with an outline of its route.
Stackd is not a healthcare provider and is not covered by HIPAA. Please do not use Stackd to store records you need HIPAA protection for.
Wherever you live, you can:
We respond within 30 days and will not treat you differently for using your rights.
California, other US states, and Washington. Depending on where you live, you may have rights to know, access, correct, delete, and port your personal information, to limit the use of sensitive information, and to opt out of sale, targeted advertising, or profiling. We do not sell personal information or use it for targeted advertising or profiling. Health information you give Stackd is used only to provide the features you request, and is never shared except as described in Section 7. To use any of these rights, email support@stackd.health. You may use an authorized agent, and you may appeal our decision by replying to our response.
European Economic Area, United Kingdom, and Switzerland. If these laws apply to you, we process your information to provide the service you signed up for (contract), with your explicit consent for health data and AI features, and for our legitimate interest in keeping Stackd secure. You have rights to access, correct, delete, restrict, object, and port your data, and to withdraw consent at any time. You may also complain to your local data protection authority. Your data is processed in the United States.
Stackd is for adults 18 and over. We do not knowingly collect information from anyone under 18. If you believe a minor has created an account, email us and we will delete it.
If we make material changes, we will notify you by email or in the app at least 7 days before they take effect. The date at the top shows when this policy last changed.