MindGrain processes all data on your device. Nothing leaves your phone. There are no accounts, no servers, no analytics, and no tracking. This policy exists because Apple requires one — not because we collect your data.
MindGrain accesses the following data sources to generate cognitive rhythm insights. All processing occurs entirely on your device.
| Source | What's accessed | How it's used |
|---|---|---|
| Apple Health | Heart rate variability, sleep analysis, resting heart rate, respiratory rate, blood oxygen, wrist temperature, step count, active energy, walking speed, step length, walking steadiness, workouts | Read-only. Correlated with typing rhythm to surface cognitive wellness patterns. MindGrain never writes to Apple Health. |
| Keyboard timing | Keystroke timestamps (press/release), key categories (letter, space, backspace — not which specific key), touch position for left/right hand inference | Builds a personal typing rhythm baseline. Detects shifts in cognitive-motor fluency. No text content is ever captured. |
| Weather & air quality | Temperature, humidity, air pressure, UV index, AQI, PM2.5, NO₂, O₃ | One daily fetch using your approximate city-level location. The location is not stored — only the weather data is saved locally. |
| Motion | Device acceleration while MindGrain is open | Movement context during typing sessions. Captured only while the app is in the foreground. |
| Self-reported context | Tags you add (caffeine, stress, etc.) and daily feeling check-ins | Correlates your reported context with rhythm patterns over time. |
MindGrain includes a custom keyboard extension that captures typing rhythm metadata. iOS requires you to grant "Full Access" for the keyboard to save timing data to the app's local database. This is a technical requirement of iOS, not a data transmission permission.
The keyboard extension has zero network entitlements. It is physically incapable of transmitting data. Full Access allows writing to a shared local database (App Groups container) — nothing more.
The keyboard functions as a standard text input keyboard without Full Access. Timing data collection is paused until Full Access is granted, but typing works normally.
On supported devices (iPhone 15 Pro and later with Apple Intelligence enabled), MindGrain uses Apple's on-device foundation model to generate personalized insights and answer questions about your rhythm. This processing occurs entirely on your device using Apple's Foundation Models framework. Apple does not log these interactions, and they work fully offline.
On devices without Apple Intelligence, MindGrain generates identical insights using template-based rendering. The data and patterns are the same — only the language generation method differs.
All data is stored locally on your device in an encrypted SQLite database within the app's sandboxed container. Specifically:
You can export all your data as CSV files at any time from the app's Curate tab. You can delete all data from the same location. Deleting the app removes all local data. Backup files in iCloud Drive persist until you manually delete them from Files.
MindGrain is not directed at children under 13. We do not knowingly collect data from children.
MindGrain uses two open-source libraries: GRDB.swift (local database) and KeyboardKit (keyboard rendering). Neither transmits data. Both include Apple-required privacy manifests declaring no data collection.
If this policy changes, the updated version will be posted at this URL. The effective date at the top will be updated. MindGrain does not collect email addresses, so we cannot notify you directly — check this page if you want to review changes.
MindGrain is built by the MindGrain team, based in Zurich, Switzerland. For privacy questions: hello@mindgrain.app
MindGrain is a wellness application. It is not a medical device and does not diagnose, treat, cure, or prevent any disease or medical condition. All insights are informational and do not constitute medical advice.