ONYXOnyx: Fitness & AI Coach is made by The Miller Brand ("we"). This policy explains what Onyx reads, what leaves your iPhone, who handles it, and how to remove it. The short version: your health data lives on your iPhone. Some of it goes to our AI provider, Anthropic, only when you use a feature that needs it, only after you've given Onyx permission, and only to answer you. Your health data is never sold or used for advertising.
1. What Onyx reads from Apple Health
Only what you allow in the Health permission sheet, and only to compute your scores, trends and Coach's reads:
- Activity: steps, active and resting energy, exercise and stand time, distance (walking, running, cycling, swimming), stair speed, workouts.
- Heart: heart rate, resting heart rate, heart rate variability, walking heart rate, cardio fitness (VO₂ max), high/low heart rate and irregular rhythm notifications, AFib burden.
- Sleep and recovery: sleep stages and times, respiratory rate, sleeping wrist temperature.
- Body: weight, height, BMI, body fat, lean mass, waist circumference.
- Mobility: walking speed, step length, asymmetry, double support, steadiness, six-minute walk distance, falls.
- Other health records you may have in Health: blood pressure, blood glucose, menstrual flow (to put recovery in the context of your cycle), water, caffeine and alcoholic drinks, mindful minutes.
- Characteristics: date of birth and biological sex, used for calorie and heart-rate calculations.
- Health Records lab results, only if you choose "Connect Health Records": the lab results your provider has shared with Apple Health. Onyx reads them into your Labs, on your iPhone; they never pass through our server or go to iCloud.
Items in bold are sensitive. Onyx does not use any Health data for advertising or marketing, and never sells it.
2. What Onyx writes to Apple Health
When you ask it to: workouts you record (with heart rate, distance and, for outdoor sessions, the route), weigh-ins and body measurements you enter, and — unless you turn it off in You → Privacy & data — the meals you log, with their calories and nutrients. Edits and deletions in Onyx are reflected in Health.
3. Location
Onyx uses your location only while a run, walk, ride or hike you started in Onyx is in progress, to measure distance and pace and draw the route. The route is saved to Apple Health with the workout. It is not sent to our server.
4. On your iPhone, and Apple Intelligence
Scores, trends, the notification plan, food scores and most of Coach's written reads are computed on your iPhone. Where Apple Intelligence is available, Onyx's written summaries — and the reading of a training goal you type in your own words — are produced by Apple's on-device model. We don't receive that data.
5. Our server and our AI provider (Anthropic)
Some features need a larger model than your iPhone has. For those, Onyx sends the minimum needed to our server (hosted by Railway, in the United States), which forwards it to Anthropic, PBC (the maker of the Claude AI) and returns the answer.
Onyx asks first. The first time you use one of these features, Onyx shows what will be sent, who receives it and what happens to it, and sends nothing unless you tap Allow. You can turn it off any time in You → Privacy & data → AI features; with it off, these features are unavailable and nothing is sent. Everything else in Onyx keeps working.
What each feature sends:
| Feature | What is sent |
|---|---|
| Coach chat | Your messages, recent conversation, facts you've asked Coach to remember, the training goal you typed (if you set one), the names and distances of places to eat near you when you ask Dot for them (your location itself stays on your iPhone), and a summary of your current numbers (readiness, sleep, training, nutrition targets, and your age, sex, height and weight). Not your name. |
| Log a meal by description or photo | The text, or the photo of your meal. |
| Menu scan | A photo of the menu. |
| Lab import | Photos or PDF pages of your lab report. These often show your name; you can crop it out — only the results are needed. |
| Meal plan, swaps, pantry recipes | Your targets, preferences, the ingredients you list, and the training goal you typed (if you set one). |
| Your own training goal | The words you type, only when no Apple model on your iPhone can read them. |
| Food alternatives | The product's name and nutrition. |
| Build a workout / new exercise | Your request, or the exercise name. |
| Written reads (fallback) | A summary of the metric being described, when no Apple model is available. |
Each Coach message is also checked, before Coach answers, for signs of a medical emergency, self-harm or disordered eating, so Onyx can show the right help instead of coaching. That check uses Claude too and sees only the message itself. Results from your Health Records are never sent, and neither is your location (only, when you ask Coach for somewhere to eat, the names and distances of nearby places).
Our server does not store the content of these requests; it is processed to return the answer and discarded. Operational logs may briefly record that a request happened and whether it failed. Anthropic processes the content under its commercial terms, which do not permit training on it, and deletes it within 30 days — longer only if its automated safety systems flag a request for review. Requests carry no name, email or account identifier.
6. Proving it's really Onyx, and that you have Pro
To stop our server being misused, Onyx uses Apple's App Attest: your iPhone creates a key in its secure hardware and Apple confirms it belongs to Onyx on a genuine device. When you have Pro, Onyx sends Apple's signed record of your purchase (product, dates and transaction ID — no name, email or payment details) so the server can confirm it. These produce a short-lived token stored on your iPhone. We don't link them to you.
7. Anonymous usage and diagnostics
Unless you turn off You → Privacy & data → Share anonymous usage, Onyx sends:
- Usage events — for example that onboarding was completed, which screen opened the Pro offer, whether a purchase completed, which way a meal was logged — tagged with a random identifier created for this install. It is not your Apple ID, email, name or device identifier, and contains no health values.
- Diagnostics from Apple's MetricKit: crash reports, freezes, launch time and scrolling smoothness. These contain technical details about the app, not your data.
We keep these for up to 90 days to understand what's working. Turning the setting off stops both, and the ad measurement below, and deletes the install identifier.
8. Measuring our ads (Meta)
We advertise Onyx on Facebook and Instagram. To learn which ads lead people to install and subscribe, Onyx includes Meta's App Events SDK. Unless you turn off Share anonymous usage, it sends Meta (Meta Platforms, Inc.):
- that Onyx was installed and opened;
- that a free trial started or a subscription was bought — the plan, price and currency;
- technical details Meta's SDK collects with these, such as your device model, iOS and app versions, and IP address.
No health or fitness data, nothing you've logged and nothing you've told Coach is ever sent to Meta. Onyx doesn't ask for permission to track you, so Meta's SDK doesn't receive your device's advertising identifier. Meta handles this data under its own terms and privacy policy.
9. Your iCloud
If you're signed in to iCloud, Onyx syncs your settings and preferences — exercise preferences, custom exercises, workout templates, recipes, your grocery list and pantry, and how your coach looks — to your private iCloud database, which only you can access; we can't read it. No health information is stored in iCloud. (Versions before 3.7 synced some health data; Onyx 3.7 deletes it from your iCloud the first time it runs.) To remove what's there, use You → Privacy & data → Delete account & data in Onyx, or remove Onyx's data in iOS Settings → [your name] → iCloud.
10. Sign in with Apple
If you use it, Apple shares a name and an email (which may be a private relay address) with Onyx on your device. We don't send them to our server.
11. The report for your doctor
"Make a report for my doctor" builds a PDF on your iPhone from your labs and Health data. Nothing is sent anywhere until you choose to share it.
12. Notifications
Notifications are planned and scheduled on your iPhone. No notification content is sent through our server.
13. What we don't do
We don't sell data, show ads inside Onyx, or ask to track you across other apps and websites. We share data only with the companies named above (Apple, Anthropic, Railway, and Meta for ad measurement) for the purposes described.
14. Children
Onyx is not directed at children under 13, and we don't knowingly collect their data.
15. Your choices
- Turn AI features on or off in You → Privacy & data → AI features.
- Change Health permissions any time in iOS Settings → Health → Data Access.
- Turn off meals to Health or anonymous usage (which also stops ad measurement) in You → Privacy & data, and any notification in You → Notifications.
- Export everything Onyx holds (You → Privacy & data → Export everything).
- Delete your data with You → Privacy & data → Delete account & data.
- On Onyx 3.7 and earlier, these settings are under Settings → Your data.
16. Changes and contact
We'll update this page when what Onyx does changes, and note the date at the top. Questions: see the Support page in You → Help & legal.