Nextmark privacy policy
Last updated 15 October 2026
Nextmark is made by Serhii Alpieiev. This page describes what the iPhone app stores, who else touches it, and how to get it back or destroy it. It covers Nextmark only.
The short version
- There is no account. No email address, no name, no phone number, no password.
- What you log is health data, and it is stored linked to a random anonymous user ID.
- Nothing is sold, there are no ads, and nothing is shared with advertisers or data brokers.
- The app does not track you across other companies' apps or websites, and never reads the advertising identifier (IDFA).
- You can export everything, or delete everything, from Settings. Both are free, at any time.
What is stored
What you enter and log
Kept in Google Firestore under your anonymous user ID:
- Your regimen: your medication and its dose, the schedule (weekly, daily or every few days), your shot day, your preferred time, your start date and your dose history.
- Every shot: its date, time, dose and injection site.
- Your weight entries, including any you import from Apple Health.
- Your side effects: what they were and how severe.
- Your notes, the optional free text you add to a shot or a side effect.
- Your settings: units, reminder preferences and whether you finished setup.
Your weight, doses, injection sites, side effects and notes are health data, and they are linked to your anonymous user ID: that ID is the key everything is filed under. The security rules give access to that ID alone and deny every other user.
Apple Health
Weight import from Apple Health is a Nextmark Pro feature, and it is off until you turn on the switch on the Weight screen. Nextmark then reads your body-mass samples. It never writes anything to Apple Health. Readings it imports are stored as weight entries under your anonymous user ID, like any weight you type in, and are never sent to analytics or used for advertising.
What the app measures about itself
Usage events go to Amplitude and to Google Analytics for Firebase: which screens you open, which setup steps you complete, that a shot, a weight or a side effect was logged, whether a paywall was shown. Some events carry details from your log: the injection site of a shot, the kinds and severity of a side effect, how many days back an entry was dated, and whether it has a note. Your medication and your schedule are attached as user properties. Events never carry a weight reading, the text of a note or the estimated level curve.
Crashes
Firebase Crashlytics receives crash traces and error reports, your device model and iOS version, tied to the anonymous user ID, so a crash can be fixed.
How fast the app runs
Firebase Performance Monitoring measures how long the app takes to launch, how smoothly each screen draws, and how long each network request takes. It records the address of those requests with the query string removed; the subscription service's address contains your anonymous user ID. It also records your device model, iOS version, whether you are on wifi or cellular, and the country your device is set to. It records nothing you typed and nothing you logged.
Purchases
Subscription state is handled by RevenueCat on top of Apple's own receipt. Apple takes the payment; card numbers never reach the app or the developer.
Sign in with Apple
Linking an Apple ID, in Settings → Account, is optional. It requests no name and no email address, so Apple shares neither. Firebase keeps the identifier Apple issues for Nextmark alongside your anonymous user ID, which is what lets your log come back on a new phone. Unlinking removes it.
Identifiers
- A random anonymous user ID created by Firebase Authentication on first launch. It is the key everything above is filed under, and it is also the ID sent to Amplitude, Google Analytics, Crashlytics and RevenueCat so those records line up.
- A Firebase app-instance ID and your device's vendor identifier, shared with RevenueCat so a purchase can be matched to an install.
- If you arrived from an Apple Search Ads ad, Apple's attribution token. It is not the advertising identifier and it does not identify you.
What is never collected
- Your name, email address, phone number or postal address.
- Your location, contacts, photos, microphone or camera.
- Anything from Apple Health other than body-mass samples, and those only once you turn the import on.
- The advertising identifier (IDFA). There is no App Tracking Transparency prompt because there is nothing to ask for: no tracking, no data brokers, no ads.
Who processes it
| Who | What they get | Why |
|---|---|---|
| Google (Firebase Authentication, Firestore, Analytics, Crashlytics, Performance Monitoring) | The anonymous user ID, everything you log, usage events, crash traces, timings | Storing your log and keeping the app working |
| Amplitude | Usage events and the anonymous user ID | Understanding which parts of the app help |
| RevenueCat | The anonymous user ID, the two install identifiers, purchase state | Knowing whether you have Pro |
| Apple | The purchase, and the Sign in with Apple link if you make one | Taking the payment, running the App Store, restoring your log |
They act as processors on the developer's behalf and are not permitted to use your data for their own purposes. Data is stored on Google's and these providers' servers, which may be outside your own country. What you log stays in Firestore until you delete it.
Your data, in your hands
Settings → Data → Export data writes your whole history as three CSV files and a JSON file and hands them to you. It is free, unlimited and needs no subscription.
Settings → Data → Delete all data deletes your shots, weights, side effects, regimen and reminders. It cannot be undone, so export first if you want a copy. Your anonymous user ID and your purchase record survive, so a subscription you paid for keeps working. If an Apple ID is linked, Delete all data also unlinks it; you can also unlink it on its own in Settings → Account.
Deleting the app from your iPhone does not delete the stored copy. Reinstalling without a linked Apple ID starts a new anonymous user ID rather than reconnecting to the old one, so the old records become unreachable, not erased. Use Delete all data first, or email support@nextmark.mriy.io and we will delete them on request.
Because there is no account, a request by email cannot always be matched to a particular person's records. The export and delete buttons in the app do the same job immediately, from the one device that can prove it is yours.
Children
Nextmark is meant for adults recording their own prescribed treatment. It is not directed at children and does not knowingly collect information from them.
Changes
If what the app collects changes, this page changes with it and the date at the top moves. A change that materially affects what is stored will be described here rather than quietly folded in.