Chess CoachPrivacy Policy
This policy explains what personal data the Chess Coach app and this website process, why, and what you can do about it. The app also contains a shorter version of this notice that you can read offline under Help and Privacy.
Controller
Perjan ProfessionalProductPartners FlexKapG (brand: Danube Studios), Heiligenstädter Lände 29/2.OG, 1190 Wien, Austria. Company register FN 621498v, Handelsgericht Wien. Contact: chess@danubestudios.dev.
In short
- We use your data to run the coach: read your public games, analyse them and build your training.
- The app has no advertising, no analytics SDK and no tracking. It does not send your data to any AI model.
- We never ask for your Chess.com or Lichess password.
- You can export your data and delete your account in the app's Settings.
What the app processes
| Data | What exactly |
|---|---|
| Sign-in and identifiers | Sign in with Apple gives us Apple's stable user identifier for this app. We request no name and no email from Apple, so Apple shares neither. The server keeps protected credentials to manage sign-in and to revoke Apple access when you delete your account. Your account and profile also get internal IDs of ours. |
| Name | The name you want the coach to call you. A nickname is fine. |
| Profile settings | What you set under profile details: your main format, whether you have a physical board, your timezone and chess clock if you enter them, and a notification preference (kept for a future feature; the app sends no notifications). |
| Linked chess accounts | The public Chess.com and Lichess usernames you confirm, with their sync status. Whether you have a Chess.com membership, if you tell us: it only decides whether membership-only Chess.com lessons can be suggested. |
| Device identifier | A random identifier the app creates on install and keeps in the Keychain, used to keep sign-in sessions per device. It is not Apple's advertising identifier. |
| Your games | Public games fetched from the sites you link: moves, clock times, ratings, results, dates, game IDs and the opponents' public usernames as they appear in the game. Games imported from a PGN file in earlier versions of the app stay stored too. |
| Coaching data | Your snapshots, the focus you choose, your stretches and the steps you complete or skip, game reviews, position and card attempts, export and deletion requests. If you used an earlier test version, also the AI coaching choice you made then, follow-up questions you typed about your games, and the text an AI model wrote for you. |
| Diagnostics | For each request to our server: method, path, status, request ID, duration, and the app's platform, version and build. For background tasks such as an analysis: task ID, stage, attempt, run times, error codes and your account ID. Our logs never contain request bodies. |
We do not collect your email, phone number, address, contacts, location, photos, health or payment data. Our own logs and database do not store IP addresses: rate limits use only a one-way hash of them. Our hosting provider's access logs do contain IP addresses (see below).
Why, and on what legal basis
We process the data above to provide the coach you signed up for: reading your games, analysing them, building and recording your training according to your profile, and keeping your account secure (Art. 6(1)(b) GDPR). Diagnostics and security logs serve our legitimate interest in a reliable, secure service (Art. 6(1)(f) GDPR). We do not use your data for advertising, sell it, or build profiles beyond your coaching.
Engine analysis, not AI
Stockfish, an open-source chess engine, analyses your games on our own server. Explanations in the app use fixed wording. This version of Chess Coach sends none of your data to a third-party AI model.
Who receives data
- Render Services, Inc. hosts our server and database in Frankfurt, Germany, as our processor. Render's HTTP access logs include your IP address and are kept under Render's retention.
- Apple handles Sign in with Apple, under Apple's own privacy policy.
- Chess.com and Lichess receive our requests for the public accounts and public games you link. We send them the public username; nothing else about you.
- Cloudflare, Inc. delivers this website and forwards email to us; PostHog Inc. (EU data region) receives this website's page-view and signup events. Cloudflare also stores the waitlist (see below). Neither receives data from the app.
- No AI provider, advertiser or data broker receives your data.
Where a provider may access data from outside the EU/EEA, the transfer is based on the EU–US Data Privacy Framework or EU standard contractual clauses.
On your iPhone
Session credentials are stored in the iOS Keychain. The app keeps a dated copy of your Improve screen, games and Progress so they stay readable offline, along with unsent drafts and, after a deletion request, a deletion-status file. The app does not request notification permission and sends no push notifications.
How long we keep it
We keep your data while you have an account. Server logs are kept under our hosting provider's log retention. Unlinking a site in Settings stops new reads from it; games already imported, and the reviews and stretches built on them, stay on your account until you delete it.
When you delete your account in Settings, you are signed out, other sessions are revoked, your links, games, reviews, stretches, coaching choices, follow-up questions and task records are removed, your profile and its settings are replaced with an empty placeholder and Apple access is revoked where possible. Backups are not wiped instantly: our backups allow recovery of the previous three days, and separate backup exports are kept for at least seven days. If a backup is ever restored, deletions made since then are applied again.
An account export contains your profile, games and coaching data, including anything from earlier test versions; it leaves out sign-in credentials and raw engine output. It is available for download for 24 hours. A copy you save or share is yours and doesn't expire.
This website
chess.danubestudios.dev is delivered by Cloudflare, Inc., which processes your IP address and technical request data to deliver the pages and protect them against attacks.
To see which channels bring visitors, our server records a page-view event each time a page is loaded. The event holds: the page address, with only our own campaign tags kept from the link (such as utm_source=tiktok; any other parameters are dropped); the address of the site that linked to us, reduced to its domain (for example https://www.tiktok.com, never the page or search terms); your browser's user-agent string (browser, operating system and device type); the country Cloudflare derives from your IP address; the time; and a random event ID that is new for every event. No script runs on your device for this, no cookies are set, and nothing is stored on or read from your device. Requests from known bots, link previews and browser prefetches are not recorded. Links from our social media profiles may pass through go.danubestudios.dev, which records the click in the same way.
We store neither your IP address nor any identifier, and we do not link page views to each other or to you. They are not anonymous in the strict sense: someone who already knew the exact time of your visit and your browser's user-agent string could match one event to it. We hold no such information and never try. The events are processed by PostHog Inc. in its EU data region and kept for up to seven years, PostHog's retention period on our plan; PostHog offers us no shorter setting. Legal basis: our legitimate interest in knowing which channels bring visitors (Art. 6(1)(f) GDPR). Because the events hold no identifier, we cannot find or single out the page views of a particular visitor. See also the Danube Studios privacy policy.
The waitlist
If you join the waitlist on this website, we store your email address, the time you signed up, which version of the notice beside the form you agreed to, and the campaign tags of the link that brought you (for example that you came from our TikTok profile). We use your address only to tell you when you can start using Chess Coach and to send you your invite. We don't add you to a newsletter and don't pass your address on. Our first email to you asks you to confirm your address, and we send your invite only after you have confirmed it. The PostHog event for a signup contains the campaign tags, never your email address.
To stop automated signups, Cloudflare's rate limiter counts form submissions per sender for one minute. It receives a one-way hash of your IP address, not the address itself, and we store neither.
Your address is stored with Cloudflare, Inc. in a database located in the EU. Legal basis: your consent (Art. 6(1)(a) GDPR), which you can withdraw at any time by emailing chess@danubestudios.dev; every email we send you about the waitlist will say how to leave it. We delete your address when you ask, and at the latest 12 months after we have sent your invite or after Chess Coach becomes publicly available, whichever comes first. Before we send the first email, we will name here the service we use to send it.
Emailing us
If you email us, we process your message and contact details to answer it. Emails reach us through Cloudflare Email Routing and are stored in our Google Workspace mailbox. Legal basis: Art. 6(1)(b) and (f) GDPR. We delete correspondence when it is no longer needed, subject to statutory retention periods.
Your rights
You have the right to access, rectification, erasure, restriction of processing, data portability, and to object to processing based on legitimate interests. Export and deletion are built into the app's Settings; for anything else, email chess@danubestudios.dev. You can also complain to the Austrian Data Protection Authority (Datenschutzbehörde, dsb.gv.at).
Changes
We update this policy when what the app or this website does with data changes. The date above shows the latest version.