Kaizen Sudoku Privacy Policy

Effective 21 August 2026 · Last updated 21 August 2026

Kaizen Sudoku (“the app”) is an iOS and Android puzzle app published by Matter ApS (“we”, “us”, “our”), a company registered in Denmark.

The short version: Kaizen Sudoku does not require an account, an email address, or a name. The app links your gameplay to your device using an anonymous identifier so your progress, stats, and puzzles carry over between sessions, and so weekly-challenge and friends features can work. We do not sell data, run ads, or use any analytics or tracking SDK.

1. What we collect

Anonymous device identity. On first launch, the app creates an anonymous identifier for your device (via Supabase’s anonymous authentication) and a locally generated device ID. Neither is an advertising ID, and neither is linked to your name, email, or any other real-world identity unless you choose to add a display name. This identifier is what lets your stats and puzzle progress sync across app restarts and, if you reinstall on the same device, resume where you left off.

Optional display name. You may set a display name in Settings, shown to friends you connect with and on the weekly-challenge leaderboard. This is entirely optional — the app works fully with no name set — and you choose what to put in it.

Gameplay data. The app’s learning engine tracks how you solve puzzles: which cells you select, which digits you place, notes you toggle, hints you request, mistakes you make, and the timing between these actions. This is used to generate a short insight after each game, track your progress toward each Sudoku solving technique, and compute your stats (games completed, streaks, best times per difficulty).

Social data. If you invite a friend or accept an invite, the app links your two anonymous identifiers as a friendship so you can see each other on a friends leaderboard. If you play a weekly challenge, your completion time and hint usage for that challenge are recorded to rank you against friends who also played it.

We do not collect: your name (unless you type one into the optional display-name field), your email address, your phone number, your location, your contacts, or any advertising/tracking identifier. The app does not integrate any analytics, crash-reporting, or advertising SDK.

2. Where this data is stored

All of the above is stored in a Supabase-hosted PostgreSQL database, in the eu-west-1 (Ireland) AWS region. Supabase is our infrastructure provider — the equivalent of a data processor — and does not use your data for its own purposes. It is governed by Supabase’s own privacy policy.

We do not share this data with any other third party, and we do not sell it.

3. Data retention and deletion

Your gameplay data, stats, and any display name persist for as long as you use the app, so the learning engine can track your progress over time.

You can delete all of it yourself at any time: open Settings → Delete My Data. This immediately and permanently deletes your anonymous user record and everything linked to it — games, gameplay events, stats, friendships, and challenge entries — with no need to contact us. The app then starts fresh with a new anonymous identity, as if newly installed.

4. Children

Kaizen Sudoku is not directed at children under 13, and we do not knowingly collect data from them.

5. Changes to this policy

We may update this policy. Material changes will be reflected by updating the “Last updated” date above and posting the revised policy at this page.

6. Contact

Questions about this policy or your data:

Matter ApS
Email: support.kaizensudoku@matteraps.com

Governing law: Denmark.