What AI Chess Coach 3D knows about you

The app saves the following locally, in Android's own SharedPreferences storage:

• The game in progress, so you can resume after closing the app.
• Your game history — finished games as PGN, including result, move count, and date, capped at the 200 most recent games.
• Your settings — preferred side, engine difficulty, 3D board on or off, AI coach on or off.

This data is not transmitted to us or to anyone else. It is removed when you uninstall the app or clear the app's data from Android Settings. If you use Share PGN, the game text is handed to the app you pick — mail, messaging, a file — and that destination's own privacy terms then apply.

Pro is sold through Google Play, with RevenueCat managing entitlements and receipt validation.

• We never see or handle your payment details. Card and billing information goes to Google and is never available to us or to this app.
• The app does not create an account or ask for an email address. RevenueCat assigns an anonymous app user ID — a random identifier not linked to your name — and uses it to remember what you have purchased and to restore purchases on request.
• To operate the purchase, RevenueCat and Google Play process: the anonymous user ID, the purchase receipt and subscription status, the product purchased, device model, Android and app version, and a country derived from your IP address.
• Restore purchases asks Google Play and RevenueCat for the entitlements attached to your Google account.

We use this data only to decide whether Pro is unlocked, and to see anonymous, aggregate revenue figures. We do not use it for advertising and we do not sell it.

RevenueCat handles this data on our behalf — as our processor, under its data processing agreement, and only for the purposes above. Google Play is the seller of record for the transaction and an independent controller of the payment details it takes from you directly, which never pass through us. Their policies: Google, RevenueCat.

Two features send data to our AI service, which runs on Fly.io.

Opening Explainer — after a game ends, sends the board position (FEN), the first 20 moves in standard notation, the opening's ECO code, and your language preference.

Position Chat — sends the same position data, your recent messages in that conversation (bounded to the last several turns), and the message you type, which is limited to 500 characters.

What this means in practice

• These requests carry chess data and your typed question only. The app does not attach a user ID, account data, device identifier, advertising ID, or location to them.
• Your IP address reaches our server as an unavoidable part of any internet request. We use it only for short-term rate limiting — held in memory for a rolling 60-second window, never written to a database, never used to build a profile.
• Our database stores only the chess opening reference corpus the answers are drawn from. No user request is written to it. Server logs record errors for reliability purposes; they are not used to profile users and are retained only briefly.

Please do not type personal information into the chat box. It is a free-text field, so anything you write there is sent to our service and on to the model provider named below. Keep it to chess.

Third-party language model

To compose the wording of an answer, our service forwards the position and your question to Google's Gemini API, which generates the response text. We use the API's paid tier, through a Cloud project with active billing. Under the Gemini API terms for paid services, Google does not use prompts or responses to improve or train its models, and processes them as a data processor under its Data Processing Addendum. The human review Google applies to its free tier does not apply to paid requests, and we do not use the free tier.

Google does, however, log prompts and responses for a limited period — solely to detect and prevent abuse of its usage policy, and for any legally required disclosure. That logging happens on Google's systems; it is not visible to us and we never receive it. Google states this data may be stored or cached in any country where it maintains facilities. See also Google's privacy policy.

If the model is unavailable or its answer fails our validation, the app falls back to text composed from our own reference corpus, and nothing further is sent.

These features are optional: they only run when you open the Chat screen or ask for an opening explanation.

The Move Coach, Game Summary, and Rules Q&A features run entirely on your device.

Rules Q&A uses Android's built-in on-device AI, where your device supports it, to phrase its answer. The Move Coach and Game Summary do not use an AI model at all: their text is computed deterministically from the chess engine's own analysis of your game. No model is downloaded for any of these features, and none of them sends anything anywhere.

Nothing about your games is uploaded for these features, and they work with no network connection.

The app requests only the INTERNET permission. It does not ask for contacts, location, camera, microphone, photos, or storage permissions, and it has no access to them.

AI Chess Coach 3D is not directed at children under 13, or the equivalent minimum age in your country, and we do not knowingly collect personal information from children. Since the app collects no identifying information at all, there is nothing for us to delete on request; purchases made by a minor should be raised with Google Play.

Depending on where you live — for example under the GDPR in the EU and UK, or the CCPA/CPRA in California — you may have rights to access, correct, delete, or port your personal data, and to object to its processing. We do not hold data that identifies you, so in most cases:

• To delete everything the app stores about you, uninstall the app or clear its data. This removes your games, history, and settings permanently — we hold no copy.
• For purchase data, contact RevenueCat or Google, who hold it.
• For anything else, open an issue and we will respond within the period your local law requires. The issue tracker is public — please do not post personal details in it.

We do not sell or share your personal information as those terms are defined under California law, and we do not engage in targeted advertising.

Our AI service is hosted in the region configured on Fly.io, and Google may process model requests outside your country — its terms allow prompts and responses to be stored or cached in any country where Google maintains facilities. Where data leaves the EEA or the UK, transfers rely on the standard contractual clauses those providers maintain.

Traffic to our AI service, to Google Play, and to the Gemini API uses HTTPS. Requests to the AI service are size-limited and rate-limited. Because the app stores no credentials and holds no account, there is no login to compromise. No system is perfectly secure, but the amount of data at risk here is deliberately kept near zero.

If we change how the app handles data, we will update this page and the "last updated" date above. Material changes will be noted in the app's release notes. Continuing to use the app after a change means you accept the revised policy.

Questions about this policy or about your data: open an issue on GitHub. The tracker is public, so please do not include personal details.