LAST UPDATED — AUGUST 30, 2026
The short version: Sudoku has no ads and never asks you to create an account, and nothing about you is sold or given to data brokers. We never ask for your name, email, or any other personal detail. We assign your device a random identifier so the puzzles you've played and your rating stay with you. Your identifier and both of those live on our servers at Cloudflare, and we use Google Firebase to spot crashes and slow screens and to see which parts of the app get used. If you want your achievements backed up you can sign in to Game Center or Google Play Games — that is optional, it uses an account you already have, and we never see it.
This policy covers the Sudoku app by Syness Studios LLC. It sits alongside our general privacy policy. Where the two differ, this one governs Sudoku.
Sudoku is operated by Syness Studios LLC, a Colorado limited liability company.
Privacy questions: [email protected]
Sudoku has no accounts of its own, and never asks you to create one. Instead, the first time you open the app it generates a random identifier and stores it on your device. Where your platform supports it, that identifier is anchored in iCloud Keychain (iOS) or Block Store (Android) so the same identifier is restored when you reinstall the app or set up a new device on the same platform. That carries your rating and the puzzles you've already played. Puzzles in progress, your notes and your saved shelf are stored only on your device — they do not transfer, including between iOS and Android.
That identifier is associated on our servers with the puzzles you've played and your rating. Your solve times stay on your device. We use it only to serve you puzzles you haven't seen and to keep your statistics accurate.
The identifier is not derived from anything about you or your device. We cannot connect it to your name, email address, phone number, Apple ID, or Google account, and we do not try to. But because it is persistent and tied to your play history, we treat the data behind it as linked to you rather than anonymous, and we describe it that way in our App Store privacy disclosures.
Sudoku has achievements, and it works out which ones you have earned on your own device, from the puzzles you solve. None of that needs an account or a network: a player who never signs in anywhere earns them, keeps them and sees them exactly the same way.
If you want them backed up and shown on your platform profile, you can sign in to Apple Game Center on iPhone and iPad, or Google Play Games on Android. The app never asks at launch. It offers once, after you have earned something, and the offer is also parked on the Achievements screen for whenever you want it. Declining costs you nothing and is not asked again.
Signing in uses an account you already have with Apple or Google. Sudoku creates no account of its own and there is no form to fill in — but on Android, if you do not already have a Google Play Games profile, accepting the offer hands you to Google's own flow for creating one, and that profile is Google's, not ours.
While you are signed in:
On Android, Google's Play Games Services library is part of the app. When you are signed in, Google collects your Play Games identity and the achievements recorded against it, as its own service and under its own policy. That is why our Play Store data safety listing names user IDs and app activity once you sign in, and why it records both as optional — nothing about them is collected from a player who does not.
We use three Google Firebase services:
| Service | What it receives |
|---|---|
| Firebase Crashlytics | Crash reports: device model, OS version, app version, and a stack trace |
| Firebase Performance Monitoring | App start times, screen rendering times, and the timing and destination of network requests the app makes to our own servers |
| Firebase Analytics | In-app events — screens opened, puzzles started and completed, difficulty selected, settings changed |
All three receive a Firebase installation identifier, which is separate from the identifier described above and specific to your install of the app.
Firebase Analytics derives an approximate location — roughly country or region level — from the IP address your device connects with. We do not collect GPS location, and Sudoku never asks for location permission.
If Sudoku offers a purchase, Apple or Google processes it entirely. We receive a transaction receipt. We never see your card details.
Google (Firebase). Crashlytics, Performance Monitoring, and Analytics are Google services and are governed by Google's privacy policy. We have not enabled ad personalization signals or Google Ads data sharing for Sudoku.
Apple and Google (app stores). They handle distribution and payments under their own policies.
Apple Game Center and Google Play Games. Only if you sign in, and only your achievements. They are held against your own platform account under Apple's and Google's privacy policies. Nothing else about your play reaches them — see section 2.
Cloudflare. Our servers run on Cloudflare (Workers, D1, KV and R2). Your anonymous identifier, the puzzles you have played and your rating are stored there on our behalf, under Cloudflare's privacy policy.
That's the complete list. Nobody else receives data from Sudoku.
Sudoku is intended for a general audience. We do not knowingly collect personal information from children under 13. If you believe a child has provided us personal information, contact [email protected] and we will delete it.
You can ask us to tell you what data we hold, correct it, delete it, export it, or stop processing it. If you live in the EEA, UK, California, Colorado, or another US state with a comprehensive privacy law, you have these rights by law. Everyone else has them because we extend them by policy.
Because Sudoku has no account of ours to look you up by, we need your anonymous identifier to locate your data. Email us at [email protected] and we will walk you through retrieving it. If you have deleted the app, we may be unable to locate your data at all — in that case there is nothing of yours left for us to hold. We'll respond within 30 days. We will not retaliate or charge you for making a request.
In the app, on iPhone and Android: Settings → Account → Delete account. This erases your server-side progress, discards your identifier, and issues a new one. It cannot be undone.
By email: send your anonymous identifier to [email protected].
Deleting the app without deleting your data first will leave your progress on our servers, and your identifier may be restored from iCloud Keychain or Block Store if you reinstall.
Achievements held by Apple or Google. Deleting your data here erases everything we hold, including the achievements kept on your device and any that had not yet been sent to a platform. It cannot reach the copy Game Center or Play Games holds, because that copy belongs to your Apple or Google account rather than to us.
If you sign in to a platform again after deleting your data here, achievements you earned before can reappear from that platform account. That is your Apple or Google account working as intended, not a copy we held on to.
Retention. Puzzle progress is kept while the identifier remains active and for 30 days after a deletion request. Crash, performance, and analytics data is retained for up to 90 days and then aggregated. Transaction and tax records are kept for seven years to comply with US tax law. Achievements mirrored to Game Center or Play Games are not ours to keep or to delete: Apple and Google hold them against your platform account, for as long as that account holds them — see section 7.
Security. Data in transit is encrypted with TLS. Data at rest is encrypted by our hosting providers. No system is perfectly secure; if a breach occurs, we'll notify affected users as required by law.
Where data is stored. Sudoku is operated from the United States by Syness Studios LLC, and the providers we use, Cloudflare and Google, are US companies. The databases holding your identifier, the puzzles you've played and your rating run in western North America. Playing from the EEA or the UK means your information is transferred out of the EEA or the UK to those US companies.
Cloudflare and Google are the providers your data is sent to; the app stores handle their own data under their own policies. Our agreements with both cover those transfers. Each includes the Standard Contractual Clauses approved by the European Commission under Article 46(2)(c) of the GDPR, and the UK International Data Transfer Addendum for UK data. These apply whenever the transfer is not already covered by a European Commission adequacy decision for that provider. You can read Cloudflare's data processing addendum and Google's data processing terms, or write to [email protected] and we'll send you a copy.
When we change this policy, we'll update the date at the top and post the change at syness.io/sudoku/privacy. For material changes we'll also describe them in the app's release notes.
Privacy questions: [email protected]
General inquiries: [email protected]
Syness Studios LLC, 1500 N Grant St, Ste N, Denver, CO 80203