Effective 27 September 2026
The short version. Diastra reads the health data your iPhone and Apple Watch already record, does the math on your iPhone, and keeps your Apple Health records and your training history there. They are never uploaded, and Diastra keeps no database of them.
A few things do leave your iPhone, and section 4 names every one: worked-out figures sent to Anthropic to be written as sentences (you can switch this off), the first name you type for the spoken welcome, your account email and your purchases, notes you choose to send, and a run's starting point sent to Apple to name the place and look up the weather.
The website, diastra.app, records visits to learn which parts of the page help people, and saves the bands answers a visitor agrees to save. Section 16 describes all of it, and the Consumer Health Data Privacy Policy covers the answers in detail.
Diastra never sells your data. It does not give it to advertising companies, and it is not used to train anyone's AI model.
Diastra is made and sold by Diastra LLC, 139 N Dobson Rd, Apt 404, Mesa, AZ 85201-6055, United States. Diastra LLC decides how the personal information described here is used, which makes it the controller in European law.
For anything about this policy or your data, write to support@diastra.app.
This policy covers the Diastra iPhone app, the Diastra Apple Watch app, your Diastra account and the website at diastra.app. Sections 3 to 15 are about the apps and your account, and section 16 is about the website. The Consumer Health Data Privacy Policy adds the detail that Washington, Nevada and Connecticut law asks for. This policy does not cover Apple Health, the App Store or any other company's own service, which each have their own privacy policy.
Diastra asks Apple Health for permission to read the types below. You choose which ones to allow on Apple's own permission sheet, you can change your mind at any time in the Health app under Sharing, and Diastra reads nothing at all until you allow it.
The Apple Watch app reads heart rate, active energy, walking and running distance and workouts while it records a session.
Height, body mass, date of birth and biological sex are used to work out your heart rate bands, estimate VO₂max, and set training targets. They are used for nothing else.
If you decline a type, Diastra keeps working on whatever it does have and tells you what it cannot read.
Diastra also keeps what you type into it, such as your first name, your sex when Apple Health has none, a maximum heart rate, your goals and your corrections to a workout. Section 8 says where they are kept.
The math runs on your iPhone. Your Apple Health records are never uploaded, and Diastra keeps no database of them anywhere, so no Diastra server keeps your heart rate history, your workouts or your routes.
This section lists everything the Diastra apps send off your iPhone, and why.
Diastra sends already-worked-out figures to Anthropic PBC, the company behind Claude, over the Claude API. Anthropic phrases them. It never chooses what to say, never picks a number, and never decides your training. Every figure it is given was computed on your phone first, and any number it writes that was not supplied to it is rejected before it reaches the screen.
This is switched on when you install Diastra. You can turn it off at any time, as described below.
These figures pass through a small relay Diastra operates, at diastra.app on Cloudflare,
on their way to Anthropic. Version 1.1.1 and earlier of the app reach it through
diastra.netlify.app, run by Netlify, which only passes the request on to that address. The
relay exists for one reason: it holds the Anthropic key, so the key does not have to ship inside the app
where anyone could read it out. It forwards the request and returns the sentence. It keeps no
database, writes no log of what you sent, and stores nothing. Nothing is ever sent to it for
narration unless "Write my reads with AI" is on.
What is sent is limited to short derived values, for example
You can turn this off. In Diastra, go to Profile, then Data & privacy, and turn off "Write my reads with AI". Nothing leaves your iPhone for narration after that, and every reading is written on your phone from your own numbers instead. You keep every figure. Only the phrasing changes. Turning it off also deletes the cache described in section 8.
What is never sent to Anthropic
Anthropic acts as a processor for this. Under Anthropic's commercial terms, API inputs and outputs are not used to train its models. Anthropic's privacy policy is at anthropic.com/legal/privacy.
Anthropic processes this data in the United States. If you are in the EEA, the UK or Switzerland, that is an international transfer, and it relies on the European Commission's Standard Contractual Clauses.
While you set up Diastra, the voice screen plays a short welcome in each voice you can pick, and the welcome says the first name you typed. To make that recording, Diastra sends your first name and the voice through the same relay to ElevenLabs, which turns the sentence into speech and sends the audio back. The relay does not store the name. The audio is kept on your iPhone, so it is made only once. If you type no name, nothing is sent and the app plays a recorded welcome without a name. ElevenLabs' privacy policy is at elevenlabs.io/privacy-policy.
Diastra asks you to make an account when you set it up. Your email address, or what Sign in with Apple shares, goes to Diastra's account server. Section 6 describes the account in full. It never receives a heart rate, a workout, an age or a band.
A plan bought in the app is sold and billed by Apple. Diastra never sees your card or your Apple ID. The app attaches your Diastra account id to the purchase, so the messages Apple sends Diastra about it (a free week starting, a renewal, a cancellation, a refund or a failed payment) join your account. Those messages carry the product, the price, the dates and the App Store country.
A plan bought on diastra.app is paid through Stripe, Inc. Stripe collects your card details directly, and Diastra never sees the full card number. Diastra keeps the email address, the plan, its status and dates, the amount, and the ad or link the purchase came from. After you sign in, the app asks Diastra's server whether your account holds a plan bought on diastra.app. Stripe's privacy policy is at stripe.com/privacy.
If you send a note from the app, Diastra receives the note, any way to reach you that you add (an email address or a phone number, for example), the Diastra and iOS versions, and the time. No Health data travels with it. Notes are stored with Cloudflare and read only by Diastra LLC.
If you type a friends pass code, the code is sent to Diastra's server to be checked, and the app checks the pass again about every 30 days.
Diastra uses services Apple runs inside iOS. When a workout has a route, its starting point is sent to Apple to name the place, such as "Twin Peaks · San Francisco". For a run that has no weather saved with it, the run's starting point and time are sent to Apple Weather to look up the temperature and humidity. Route maps are drawn with Apple Maps, and the music controls use Apple Music. Apple handles these requests under Apple's privacy policy. Diastra LLC does not store the coordinates on any server, and they never reach Anthropic or ElevenLabs.
| Company | What it does for Diastra | What it receives |
|---|---|---|
| Anthropic PBC | Phrases reads as sentences | Worked-out figures (4a) |
| ElevenLabs | Makes the spoken welcome | The first name you typed (4b) |
| Cloudflare, Inc. | Runs diastra.app, the relay and the account server, and stores notes and website recordings | Everything in 4a to 4e passes through it, and it stores notes (4e) and website data (16) |
| Supabase, Inc. | Runs Diastra's database and its sign-in service | Your account, your purchases and the website's saved answers (6, 4d, 16c) |
| Customer.io | Sends sign-in codes and emails you asked for | Your email address |
| Stripe, Inc. | Takes payment on diastra.app | Your payment and billing details (4d) |
| Apple Inc. | App Store purchases, Sign in with Apple, maps, place names, weather and music | See 4d and 4f |
| PostHog, Inc. | Counts website visits | See 16b |
| Netlify | Passes requests from version 1.1.1 and earlier on to diastra.app | Those requests, on their way through (4a, 4b, 4e) |
Apple, Stripe and Google also handle some of this under their own privacy policies. Every other company here works only on Diastra's instructions and may not use this data for itself.
The Diastra app on Apple Watch saves the workout you record into Apple Health, so it joins the rest of your training history. That is the only thing Diastra ever writes.
The iPhone app also asks for permission to write workouts, for one technical reason. iOS does not tell an app when a user has denied read access, so an empty Health app and a blocked Health app look identical from inside the app. Write permission is the one signal iOS reports reliably, so it is used to tell those two cases apart and show you the right screen. The iPhone app never writes anything.
Diastra asks you to make an account when you set it up, with a 6-digit code sent to your email address or with Sign in with Apple. There is no password. If Diastra's server cannot be reached at that moment, you can go on without an account and sign in later from Profile.
Your account is kept in Diastra's database, which runs on Supabase, and the app reaches it through
Diastra's account server at api.diastra.app, which runs on Cloudflare. Supabase's sign-in
service keeps your email
address so it can send you a code. Diastra's own database keeps it only in encrypted form, each address
under a key made for that person alone. Customer.io delivers the code emails, and they carry no
tracking.
If you use Sign in with Apple, Apple gives Diastra an identifier for you and the email address you chose to share. If you use Apple's Hide My Email option, Diastra only ever sees Apple's relay address. The name Apple shares is kept on your iPhone to greet you in Profile and is never sent to Diastra's server.
The account holds your email address, how you signed in, when the account was made and last used, and your purchases (4d). It holds no heart rate, workout, age or band, and signing in does not back up or move your training history. Your sign-in is kept in your iPhone's Keychain, on that iPhone only.
Version 1.1.1 and earlier of the app have no Diastra account. In them, a sign-in with Apple or Google is kept only in the iPhone's Keychain and is never uploaded, and signing out deletes it.
This section is about the iPhone and Apple Watch apps. The website is described in section 16.
Everything Diastra derives is stored on your iPhone in Diastra's own private storage, and on your Apple Watch for the watch app's own settings. It stays there until you delete it, using any of the routes in section 9.
Your workout history, everything Diastra works out, the corrections and answers you type about your training, and the narration cache are marked so they are left out of iCloud and computer backups. A few small settings are kept in the app's ordinary settings, which iOS does include in a backup if you make one: your first name, your sex if you typed it because Apple Health has none, the maximum heart rate your history was last graded with, and your choices in the app.
Text that Anthropic returns is cached on your device so the same reading is not paid for twice. That cache holds at most 48 entries and older entries are overwritten as you use Diastra. It is deleted outright the moment you turn "Write my reads with AI" off.
Health data on your iPhone is held in Apple's own encrypted app container, which is protected by your device passcode and by iOS file protection. Your sign-in is held in the iPhone Keychain. Every request the apps and the website make travels over an encrypted connection (TLS).
Diastra's database keeps your email address encrypted under a key made for you alone, and deleting your account destroys that key. Its tables cannot be read or written with the public keys that apps and web pages use. Only Diastra's own servers and Diastra LLC, holding secret keys, can reach them. Supabase encrypts the database at rest.
No system is perfect, and no promise of absolute security is made here. What is true is that there is no central store of Apple Health data to breach: Diastra keeps no database of your health records anywhere, and the relay in section 4a stores nothing that passes through it.
| What | Why it is processed | Legal basis |
|---|---|---|
| Apple Health data | To produce your reads, bands and plan | Explicit consent, Art. 9(2)(a), given on Apple's Health permission sheet |
| Derived figures sent to Anthropic | To phrase a number as a sentence | Explicit consent, Art. 9(2)(a), withdrawable at any time with the "Write my reads with AI" switch |
| First name sent to ElevenLabs | To say your name in the welcome | Consent, Art. 6(1)(a), given by typing a name, which you can leave blank |
| Account email, sign-in and purchases | To run your account and give you what you bought | Contract, Art. 6(1)(b), and legal obligation, Art. 6(1)(c), for tax and accounting records |
| Notes you send | To answer you and improve Diastra | Consent, Art. 6(1)(a) |
| Website recordings, section counts and analytics cookies | To learn which parts of the website help people | Consent, Art. 6(1)(a), asked for before any of them start |
| Website visits counted without a cookie | To know how many people visit and where they came from | Legitimate interests, Art. 6(1)(f) |
| Bands answers saved on the website | To draw your bands and improve Diastra | Explicit consent, Art. 9(2)(a), given with the tick box |
You can withdraw consent at any time using section 9 or the privacy choices page, and withdrawing it does not affect processing that already happened.
Diastra's service providers process data mainly in the United States. Transfers from the EEA, the UK and Switzerland rely on the European Commission's Standard Contractual Clauses and the equivalent UK and Swiss terms.
Diastra holds your account, your purchases, any notes you send and anything saved on the website, and you can ask about all of it. Your Apple Health records and your training history are on your iPhone, not with Diastra, so section 9 is how you control those.
You can ask to see a copy of what Diastra holds about you, to correct it, to delete it, to withdraw a consent, or to object to a use of it. Write to support@diastra.app, from your account's email address if you have one. Diastra may ask for enough detail to find your data and confirm the request is yours, and answers within 45 days. If a request is refused, reply to that answer to appeal, and the appeal is decided within 45 days. If the appeal is refused, you may contact your state's attorney general. You may also have someone you authorize make a request for you, and Diastra may ask for proof of that. Diastra never charges more or offers less because you use these rights.
If you are in the EEA or the UK, the GDPR gives you rights of access, rectification, erasure, restriction, portability and objection, and the right to complain to your national supervisory authority.
If you are in California, the CCPA as amended gives you rights to know, to delete, to correct, to limit the use of sensitive personal information, and to opt out of sale or sharing. Diastra does not sell or share personal information as those terms are defined, and has not done so in the last 12 months. If your browser sends the Global Privacy Control signal, Diastra treats it as a request to opt out of sale and sharing. Other US states with comprehensive privacy laws give comparable rights, which are honored the same way.
| Category | What it is here | Where it comes from | Why |
|---|---|---|---|
| Identifiers | Email address, account id, IP address, a visit id, PostHog's visitor id | You and your device | Your account, sign-in, security and website analytics |
| Commercial information | Plans bought, renewals, cancellations and refunds | Apple and Stripe | To give you what you bought, and accounting |
| Health information (sensitive) | On the website, with consent: sex, age, maximum heart rate and bands. From the app: worked-out figures that Anthropic phrases and Diastra does not store | You, and Apple Health on your iPhone | To draw your bands, phrase your reads and improve Diastra |
| Internet activity | Pages, taps, scrolling, time on each section, recordings of the website, the ad or link a visit came from | Your browser | To improve the website and learn which ads work |
| Approximate location | Country and state, worked out from the IP address | Your IP address | To show the right consent choice and compare regions |
| Precise location | A run's starting point, sent to Apple only (4f) | Your iPhone | To name the place and look up the weather |
| Name | The first name you type for the welcome | You | To say your name in the welcome (4b) |
Section 4g and section 16e list who receives each of these, and sections 8 and 16 say how long each is kept.
Diastra is not directed at children. You must be at least 16 to make a Diastra account, and at least 18 to buy a plan. If Diastra learns it holds personal information from someone under 16, including an age under 16 saved on the website, it deletes it. If you believe a child has used Diastra, write to support@diastra.app.
Diastra is a general wellness product. It does not diagnose, treat, cure, prevent, predict or monitor any disease or medical condition, and it is not a substitute for professional medical advice. Talk to a qualified clinician about medical concerns, and before making a significant change to how you train.
If this policy changes, the date at the top changes with it, and the current version is always at this address. A change that materially affects what leaves your device will be surfaced in the app before it takes effect, and Diastra asks again before using information it already holds in a new way that needs your consent.
This section covers visits to diastra.app. The website works differently from the apps: it records visits to learn which parts of the page help people, and it saves the bands answers a visitor agrees to save.
The website records how a visit moves through the page, so Diastra can see which parts help people and which parts confuse them. A recording keeps the page's layout and text, where the pointer or finger moved, taps, scrolling and the time spent on each section. It is played back as a picture of the page, not as a video of the screen.
The website also counts taps, the time each section holds the screen, the section where a visit ended and the named steps a visitor takes, such as pressing "Start my free trial". These counts are kept without the recording, with the page, the kind of screen (phone, tablet or laptop), the ad or link the visit came from and the country, for about three months, with Cloudflare.
A recording and its counts share a random visit id that is made fresh for each visit and kept only in the page's memory, never in a cookie.
The website uses PostHog, Inc. to count visits, pages, clicks and the steps toward starting a trial, and to tell which ad or link a visitor came from. The page reaches PostHog through diastra.app, which removes the visitor's IP address on the way, so PostHog never receives it. PostHog does receive the browser and device type.
What PostHog keeps on the visitor's device depends on where the visitor is.
Without a cookie, PostHog still counts the visit. Choosing No thanks, or turning off "Measure my visits", removes what PostHog kept on the device. A browser where "Measure my visits" is turned off sends PostHog no visit, page or click. The page still loads PostHog's script there, which asks PostHog for its settings.
PostHog does not record screens for Diastra, and it never receives a click from inside the bands section. Once a visitor has agreed to save their bands answers, PostHog also receives their sex, a ten-year age group, such as 40 to 49, and whether they typed a maximum heart rate, so Diastra can compare how different groups use the page. PostHog never receives an exact age, a heart rate or a band, and a browser that sends Global Privacy Control never sends it the sex or the age group. PostHog processes this data in the United States, for Diastra only, and keeps it for no more than seven years.
In the bands section a visitor can enter their sex, their age and, if they know it, their maximum heart rate, and the page draws their heart rate bands. When the visitor agrees to save these answers, Diastra keeps the sex, the age, the maximum heart rate typed, the maximum used and whether it was typed or estimated from the age, the bands drawn, the page, the ad or link the visit came from, the country and state, the browser type, the visit id, PostHog's visitor id, the time, and the exact words the visitor agreed to.
The answers are used to draw the visitor's bands, to improve Diastra, and to learn which kinds of visitors and which ads lead to people choosing Diastra. That learning is used, as totals across many visitors, to decide which audiences Diastra advertises to. No one visitor's answers are ever given to an advertising company, and the answers are never sold.
The answers are stored in Diastra's own database, run by Supabase, Inc., in the United States. They are kept until the visitor asks for them to be deleted. They are not linked to an email address or to a Diastra account.
The Consumer Health Data Privacy Policy describes these answers in the detail that Washington, Nevada and Connecticut law requires.
If a visitor gives an email address on diastra.app, it is encrypted before it is stored, and it is used to send what the visitor asked for and, only if the visitor agreed, emails about training and Diastra. Customer.io sends these emails, and every marketing email carries an unsubscribe link.
The buttons that start a free trial open Apple's App Store, where Apple's privacy policy applies.
Each of them works only on Diastra's instructions and may not use this data for itself. The website has no advertising pixel, and no website data is sent to an advertising company.
diastra_consent (with PostHog's own note that the browser is opted out, once
measuring is turned off), never on Diastra's servers.