Privacy Policy

Last updated: 28 May 2026

The short version. PolyPurr collects no personal data, contains no analytics, no advertising, and no third-party SDKs. The app makes no network calls. Everything you do in PolyPurr stays on your device. Uninstalling the app deletes everything.

Who runs PolyPurr

PolyPurr is a personal hobby project by Mark Haase. There is no company, no team, no backend. You can reach the developer at hello@northlab.top.

What data the app stores on your device

PolyPurr stores the following information locally, in the app's private storage area on your Android device:

The learner name you enter during onboarding (e.g. "Mark" or "Learner").
Your chosen source language, destination language, and CEFR level.
Your vocabulary practice progress: which cards you've seen, your answer history, streaks, daily quiz results.
Achievements you've unlocked.
Your settings (sound effects on/off, background music on/off, feedback timing, etc.).
Any vocabulary or study files you import yourself.

This data never leaves your device. It is not sent to the developer, to Google, or to any third party.

What data the app does not collect

No analytics or telemetry of any kind.
No crash reporting or error tracking sent to any server.
No advertising identifiers (no ads at all).
No location, contacts, microphone, camera, calendar, or call data.
No account login. There is no account.
No purchases, no subscriptions, no in-app billing.

Network access

PolyPurr does not declare the INTERNET permission and does not make any network requests on your behalf. The app is fully offline. The only exception is when you explicitly tap an external link in the "Sources & licences" screen — at that point your Android system opens the link in your normal browser, which is governed by your browser's own privacy practices, not PolyPurr's.

Android permissions

PolyPurr declares no runtime permissions. The app cannot access your photos, files, location, contacts, or any other sensitive information.

Third-party services and SDKs

PolyPurr uses no third-party analytics, advertising, crash reporting, or social SDKs. The only third-party code in the app is Android's own AndroidX libraries (Jetpack Compose, Room, DataStore, Navigation) and JetBrains' kotlinx.serialization, all running locally on your device.

Audio and content

Background music and sound effects bundled with the app were AI-generated locally by the developer (using ACE-Step, Stable Audio Open, and Meta AudioGen). The vocabulary content is project-authored; grammar tables draw from Wikidata Lexemes (CC0 public domain), with full attribution shown inside the app under Settings → Sources & licences.

Children's privacy

PolyPurr is intended for general audiences age 13 and up. It does not knowingly collect any data from children, because it does not collect data from anyone.

Managing your data

You can remove all data PolyPurr stores at any time:

Open Settings → Reset app inside PolyPurr. This wipes the database, your settings, and all auto-saved snapshots, and returns you to first-launch onboarding.
Or, simply uninstall the app from Android. Android deletes the app's private storage automatically.

Changes to this policy

If this policy changes, the "Last updated" date at the top of this page will change too. Material changes will also be summarised in the app's release notes on the Google Play listing.

Contact

Questions? Email hello@northlab.top.