Privacy policy

Last updated: 28.10.2026

1. Controller

Erdi Karasungur, Bieberer Str. 52, 63065 Offenbach am Main, Germany, email: support@denkarena.com

2. Principle

DenkArena works without an account and without your name. Progress is stored on your device first. To balance colour assignments, we store at most the last 20 colours from completed automatic-matchmaking games for each account. From the start of collection, we also count rated online wins, draws and losses separately for White and Black. Games against friends, aborted games and unrated results do not increase these totals. Other players can see these aggregate results when your profile is public; only you can see them when it is private. Sharing individual games is a separate setting. The small colour history and aggregate results remain when the game archive is cleared and are removed when the account is deleted. For “Your most common mistakes”, the app stores recognised mistake patterns and links to training positions from up to 30 of your own analysed chess games, only on this device. This mistake profile is not synced to your account or shown on the leaderboard or public profile. You can remove it under Settings → Data → Delete statistics; it is also lost when the app data is deleted. Up to twelve game analyses are cached only on this device, with evaluation values, move sequences and version information. They are not synced to your account. “Clear archive” and “Delete statistics” also remove this analysis cache. We only process data where it is needed for the app's features or where you have consented.

3. Anonymous ID and online features

For daily statistics, leagues, invites, the shop, community levels and backing up your progress, the app receives a random, anonymous ID on first launch. We store: daily puzzle results (moves, best score), league memberships and the display name you choose, invite codes (for redeemed codes also the days played during the first 14 days, so we can grant the invite reward), points and shop purchases, published levels including ratings and reports, your progress, and for online chess your player name, the moves and the result of the game, and for timed games the time spent on each move and associated clock readings (game rooms are deleted after two days; your private account archive keeps up to your last 200 completed online games, including player names, moves, results and rating changes, until you clear the archive or delete your account. This device stores up to 200 completed chess games in total, including games against the computer, two-player games on the same device and local copies of online games. Computer games and games played by two people on the same device are not uploaded to the account archive or published through profile sharing. You can clear the private archive; games stored only locally may be lost if the app data is deleted. If server space runs low, older games may be removed automatically from the account archive to leave room for core features. Copies already stored on your device are not affected. If you enable “Show my online games publicly”, other players can replay and analyse your last 200 completed online games while your profile is public. This setting starts off and can be disabled at any time. A private profile hides your own list. Your opponent can independently show the same game in their own published list. We store the visibility setting with your ID. Preset messages are stored as an identifier with the sending player and time; they are deleted with the game room after two days. For a fair play report, we also store the reporter, opponent, time, reason and a copy of the game for later review; that copy is removed when the review is closed. A limited report log is kept to prevent duplicate and excessive reports). Legal basis: Art. 6(1)(b) GDPR (providing the features you use).

3a. Profile, weekly leaderboard and reports

For your profile and the weekly leaderboard we store with your ID: display name and time of the last change, chosen avatar, frame and title, your country (derived from your device's language setting), weekly points, placings and trophies, and the “Private profile” setting. Other players see this information in the leaderboard and in your profile; with a private profile you appear there as “Anonymous” without avatar, title or profile. If you report a name, we store who reported whom and when, to prevent abuse. For online chess we also store, without reference to you, how long it took to find an opponent, to estimate waiting times (7 days). Weekly points are deleted after 8 weeks; placings and trophies stay in your profile. Messages and gifts from the DenkArena team are stored with your account. We also store which version of the terms of use you agreed to and when. Legal basis: Art. 6(1)(b) GDPR; for reports and proof of consent, Art. 6(1)(f) GDPR (protection against abuse, proof).

If you install DenkArena from Google Play using an invitation link or its QR code, the app reads the invitation code through Google Play Install Referrer on first launch and redeems it automatically for eligible new players. The code and processing status are stored on your device. To redeem it, the code is sent to our server with your app ID. This feature does not use an advertising ID. You can still enter the code manually.

Local fair-play review: To investigate reported games and unusual leaderboard patterns, authorised administrators may compare up to five completed online games of a player that are still stored, from the last 90 days, with a chess engine running locally. The review uses moves, the player’s colour and available move times. Player names, email addresses and account credentials are not passed to the local analysis tool. Results are review indicators, not proof of cheating; no account suspension or rating correction is automatic. The local review creates no permanent result copy. Temporary calculation results are replaced by the next review or discarded after 15 minutes without a new request. Existing game and report retention periods remain unchanged. This serves our legitimate interest in protecting fair competition and investigating manipulation (Art. 6(1)(f) GDPR). You may object to processing based on legitimate interests on grounds relating to your particular situation and contact us to request review of a measure.

For account administration, our admin tool shows the latest existing server contact from sign-in, progress backup, daily results or voluntarily submitted statistics. This creates no additional activity history or transmission. Offline use without a transmission cannot be inferred from it.

4. Account with email (optional)

If you back up your progress, we store your email address and send you one-time sign-in codes. So that the code email arrives in your language, we also store the app language. We use the address only for signing in, never for marketing. Code emails are sent via the email service Resend (Resend Inc., USA) with servers in the EU (Ireland). A data processing agreement is in place; possible transfers to the USA are covered by the EU Standard Contractual Clauses. Legal basis: Art. 6(1)(b) GDPR.

5. Optional usage statistics and error reports (only with consent)

During initial setup, you may separately from the terms allow us to record which games and features are used and where technical errors occur. Nothing is preselected: Without a choice, statistics remain off, and “Let’s go” does not grant consent. All app features work without consent. We record, for example, games opened and finished and, when an error occurs, the error message, affected part of the program, app version, device type and the part of the app where it occurred. Your profile name is not sent as a statistics field; known names from your own profile and email addresses are removed from error text. The data is pseudonymous, not anonymous: Requests use a user identifier, and error text may contain technical identifiers. This helps us improve the app and fix problems faster. Only existing installations that never saw this choice during initial setup and have not yet made a choice may receive a one-time question after at least five completed games, with equal choices to allow or decline. Declining or dismissing it prevents further questions. You can change your choice at any time under Settings → Data. Withdrawing consent discards pending statistics and error reports; it does not affect processing that has already taken place. Older app versions without this consent feature may still enable statistics by default; we recommend updating. Legal basis: Art. 6(1)(a) GDPR and, where information on your device is accessed, Section 25(1) TDDDG. Error reports are deleted after 60 days at the latest.

5a. Feedback

If you send us a message via “Send feedback”, we store your text together with the app version, language, device type and screen size. If you have an account and allow us to reply, we also store your email address. Legal basis: Art. 6(1)(f) GDPR (handling your request). Messages we have dealt with are deleted after 180 days.

5b. Contact by email

If you write to support@denkarena.com, your message is delivered via Cloudflare’s forwarding service (Cloudflare Inc., USA) to our mailbox at Google (Google Ireland Ltd.) and stored there so we can reply. Both providers are certified under the EU-US Data Privacy Framework. Legal basis: Art. 6(1)(f) GDPR (handling your request). We delete messages once they have been dealt with and no retention obligation applies.

6. Advertising (Google AdMob)

The free version shows ads via Google AdMob (Google Ireland Ltd., Gordon House, Barrow Street, Dublin 4, Ireland). Device and advertising IDs may be processed. Personalised ads are only shown with your consent, requested on first launch and revocable at any time (Art. 6(1)(a) GDPR). Transfers to the USA are possible; Google is certified under the EU-US Data Privacy Framework.

7. Subscription (Apple, Google, RevenueCat)

Purchases are handled by the App Store or Google Play; we receive no payment data. To verify subscriptions we use RevenueCat (RevenueCat Inc., USA), which processes the anonymous ID and purchase status. We store the subscription status reported by the app (active, expiry, renewal, platform) so we can help if there are problems. Legal basis: Art. 6(1)(b) GDPR.

7a. Wandelzug in your browser

The browser game on our website needs no account. Puzzle progress and completion of the introduction are stored only in this browser’s local storage to let you continue playing. They are not transferred to the app or our leaderboards. This browser game uses no advertising or usage analytics. You can delete its data through your browser’s website data settings. Shared puzzle links contain the puzzle date and board, but no name or solution moves.

8. Hosting (Supabase)

Online features run on Supabase (Supabase Inc.), server location EU (Ireland). A data processing agreement is in place.

9. Notifications

Daily reminders and reminders after a break can be enabled separately. Optional return reminders use the last app opening stored only on this device and are scheduled after 7 and 21 days. Opening the app moves these reminders to new dates. There are at most two return reminders per break; on those dates they replace a daily reminder, if enabled. You can turn either feature off in Settings. Notifications are scheduled locally; no usage data is sent to us for this.

10. Retention

We store data as long as you use the features. Anonymous IDs without an account that have not been used for 24 months are deleted. Usage statistics are deleted after 14 months at the latest. You can request deletion at any time.

11. Your rights

You have the right of access, rectification, erasure, restriction, data portability and objection (Art. 15–21 GDPR) and may withdraw consent at any time. Write to support@denkarena.com. You may also lodge a complaint with a data protection authority.

12. Children

DenkArena is not directed at children under 13. We do not knowingly collect data from children under 13.