Darwin Privacy Policy

Updated October 8, 2026 · Applies to Darwin on iPhone and the web

Darwin is built by an athlete, for athletes. The short version: your plan and workout summaries can be saved to your account; detailed health samples stay on your phone unless you explicitly choose optional workout-chart sync. We collect the minimum needed to run the service, we sell nothing, and we show no ads.

Apple Health and on-device processing

With your permission, Darwin reads workouts, sleep, heart rate, heart rate variability, and resting heart rate from Apple Health. Darwin uses this data on your device to track your plan, compute your readiness score, and display your workout details. With workout sync enabled, it also saves workout summaries and your corrections to your account as described below. Detailed health samples, workout streams, GPS routes, and individual sleep records are not uploaded by workout sync. Darwin does not write anything to Apple Health.

Your account

Darwin has accounts so your plan survives a lost, broken, or replaced phone. You can sign in two ways:

Sign in with Apple. We receive a unique identifier and an email address. If you choose Apple's "Hide My Email", we only ever see the relay address — we never learn your real one.
Email code. We receive the email address you type, and send you a one-time numeric sign-in code.

We store your email address (or relay address) and an account identifier. Your training profile may include the name you choose to enter. We do not ask for your phone number, date of birth, or payment details. We never receive your card details: subscriptions are billed by Apple, and we only learn whether your subscription is active.

What leaves your device

1. Your plan, so it can be restored. When you are signed in, your training plan, your weekly check-in answers, and the adjustments the engine made are backed up to our servers, tied to your account. This is what lets you sign in on a new phone and pick up where you left off. It contains your event, your race date, your sessions, and the summary figures you entered at each check-in (hours slept, how you felt, whether you fueled).

2. A weekly summary, so we can write your digest. When you complete your Sunday Refresh, a small structured summary is sent so we can generate your plain-language weekly digest. That summary contains your adherence percentage and goal status, three flags (low sleep, low feel, whether long sessions were fueled), the adjustments the engine made, your event name, and week number.

3. Workout summaries and corrections, so your recorded training can be shared across your devices. In builds that support workout sync, sync is on by default when you are signed in. A notice explains it, and you can turn it off in Settings → Account → Sync workouts to my account. Each summary may include sport, workout date, start and end times, active and elapsed duration, distance, calories, average heart rate, average power, ascent, the Apple Health workout identifier, and a device label. Your corrections include the sport, duration, distance and notes you enter, when the edit was made, and a device label. These records are tied to your account and stored separately from the Apple Health original. Darwin does not modify the original in Apple Health.

Workout sync supports keeping your edits across your iPhone and Darwin web account. Corrections use the most recent edit time to resolve conflicts. Restoring a workout saves a restore marker so an older edit from another device does not overwrite it.

Turning workout sync off removes your account's cloud workout summaries and corrections while keeping your local corrections on that iPhone. Removing cloud copies requires a network connection. Turning sync back on allows workout summaries and local corrections to be uploaded again. This switch does not turn off plan backup or weekly digest processing.

Optional detailed workout charts. If you explicitly choose Sync detailed workout charts in a Darwin iPhone version offering this feature and confirm the disclosure, recorded heart rate, speed, power and cycling cadence samples from recent workouts are uploaded to your account for web charts. Dense recordings are reduced to a bounded set of measured points retaining peaks. This does not run automatically with summary sync. Turning workout sync off removes these uploaded charts with your cloud workout records; account deletion also removes them. Availability depends on your installed app version.

Optional profile-photo sync: You may explicitly upload a selected JPEG, PNG or WebP profile photo to your private account so it appears on the web. Only your authenticated account can request access. Images are displayed using short-lived signed links. You can remove the cloud copy in iPhone or web account settings; the local iPhone copy remains. Photo sync is separate from workout sync. Account deletion removes the cloud photo before deleting the account.

What stays on your device: raw workout files, heart-rate-variability streams, individual sleep records, GPS routes or other location data, and your local profile photo. Detailed workout samples also stay on your phone unless you explicitly request the optional chart upload described above.

Who processes it

Your account, plan, synced workout summaries and corrections, and optional workout charts and profile photos are stored with Supabase (hosted in the United States), protected so that only your own account can read or write your data. The weekly summary is passed to Anthropic's Claude API solely to write your digest text; it is not used to train AI models. Sign-in emails are delivered by Resend. Subscriptions are processed by Apple and their status is managed by RevenueCat, which receives your account identifier and whether you are subscribed — not your email or any health data.

Training decisions are never made by AI. A deterministic planning engine running on your device makes every training-load decision; the AI only puts those decisions into plain words.

What we never do

No selling or sharing of your data with data brokers or advertisers
No ads, no third-party analytics or tracking SDKs
No tracking you across other apps or websites, and no advertising identifiers
No reading of contacts, photos (except a profile photo you choose, which stays on device unless you choose the optional photo sync), or location

Retention and deletion

Your plan and history are kept while your account exists. Synced workout summaries and corrections are kept while workout sync is enabled, unless you delete your account or request deletion.

You can delete everything yourself, at any time: in the app, go to Account → Delete account. That permanently removes your account, your plan, and your training history from our systems immediately. It cannot be undone.

You can also email justin@darwinendurance.com and we will delete every record tied to your account within 7 days. Deleting the app removes all on-device data immediately, but does not delete your account — use the in-app option or email us for that.

Your rights

Depending on where you live, you may have the right to access, correct, export, or delete your personal data, and to object to certain processing. The in-app delete covers deletion instantly; for anything else, email us and we will respond within 30 days. We will never charge you for exercising these rights, and we will not degrade your service for doing so.

Not medical advice

Darwin provides training guidance for healthy recreational athletes. It is not a medical device and its content is not medical advice. Consult a physician before beginning any training program.

Children

Darwin is not intended for anyone under 16. We do not knowingly collect data from children. If you believe a child has created an account, email us and we will delete it.

Beta software

Parts of Darwin are in beta, and beta builds are distributed through Apple TestFlight. Apple's own privacy terms apply to TestFlight itself. This policy may be updated as Darwin grows; material changes will be announced in the app.

Contact

Justin Ramirez · justin@darwinendurance.com