Terms of Service

1. Acceptance of these Terms

CubeXpert (the “App”) is developed and published by VisionFlutter (“we”, “us”, or “our”). These Terms of Service (the “Terms”) govern your use of the App, and of any other VisionFlutter mobile application that links to this page.

By downloading, installing or using the App, you agree to these Terms. If you do not agree to them, please do not use the App.

The App is distributed through Google Play. Your use of Google Play, and every purchase you make through it, is also governed by the Google Play Terms of Service. Where Google Play's terms and these Terms differ in relation to a purchase, Google Play's terms govern that purchase.

2. The App

CubeXpert is a cube-solving practice and learning app for Android. It provides an interactive 3D cube, six solving plans (Beginner/LBL, CFOP, Roux, ZZ, Petrus and the Kociemba two-phase solver), a two-shot camera scanner for entering the state of a physical cube, lessons and algorithm practice, solve history and statistics, and a post-solve coaching feature called the Solve Analyzer.

The App runs entirely on your device. It does not require an account, a sign-in, or an internet connection in order to scramble, solve, practise or time.

3. Your licence to use the App

We grant you a personal, non-exclusive, non-transferable and revocable licence to install and use the App on devices you own or control, for your own non-commercial use. You agree not to:

• copy, redistribute, sell, rent, sub-licence or publish the App or its assets;
• modify or tamper with the App, or attempt to circumvent the CubeXpert Pro entitlement, the free deep-analysis allowance, or advertising;
• reverse-engineer, decompile or disassemble the App, except to the extent that applicable law expressly permits this despite this restriction;
• use the App in any way that breaks the law where you are.

The App, its design and its original content remain ours or our licensors'. Third-party components keep their own licences — see section 10.

4. Eligibility and age

The App is not designed for children under the age of 13, and you should not use it if you are under 13. If you are under the age of majority where you live, you may use the App only with the involvement of a parent or guardian, who is responsible for any purchase made through your device and store account.

This mirrors the children's privacy section of our Privacy Policy.

5. CubeXpert Pro: purchases, billing and refunds

5.1) What CubeXpert Pro is

CubeXpert Pro is a one-time, non-consumable in-app purchase (product identifier cubexpert_pro_lifetime). You pay once and it stays with the store account that bought it. There is no subscription, no renewal, and no recurring charge of any kind.

5.2) What it unlocks

The Solve Analyzer's verdict on a solve — the method it detected, your time, your move count and turns per second, and the phase-split bar — is free on every solve the analyzer records, and is not part of this purchase. Pro adds:

• Unlimited coach suggestions: the analyzer's suggestions, and the drill and lesson links that go with them, after every solve rather than the weekly allowance described in 5.3.
• Deep stats: the analyzer sections of the Stats screen — method distribution, phase trends and coach insights. These are built from the analyses already stored on your device, so they include solves you completed before purchasing.
• Ad-free: no full-screen ads and no ad cards, and hint unlocks become instant.

Pro does not re-open the coaching summary for a past solve; the retroactive benefit is in Deep stats, which read the analyses already on your device.

5.3) The free allowance

The free tier is not a trial and does not expire. After a solve the Solve Analyzer records, it shows you which method it detected — or that it could not identify one — your time, your move count and turns per second, and, where it resolved the phases, the phase-split bar with the time spent in each. That is free forever and is never metered, however many solves you do.

What is metered is the deeper layer: the coach suggestions, and the drill and lesson links that go with them. Without Pro you get three of those per rolling seven-day window. The window opens when you use the first one, and once seven days have passed since it opened the allowance is back to three. It does not follow the calendar, and nothing is banked — unused analyses do not carry over into the next window.

One is used only when a solve actually produces suggestions and the analysis is saved. It is spent at the moment the analysis is saved, not when you look at it, so a solve you walk away from still counts. A solve the coach has nothing to suggest on costs you nothing. When the allowance is spent the App does not hide your summary: the method, the time and the phase splits still appear, and the suggestions are replaced by a note telling you how many there were.

The Solve Analyzer can also be switched off entirely in Settings. While it is off, no Solve Analyzer report is saved and no summary is shown to you, and no part of the allowance is used — the rest of the app, including the timer and your solve history, works exactly as before.

5.4) Price and payment

All payments are taken by Google Play, in the currency of your Google Play account, at the price shown to you at checkout. Prices are set per region within Google Play and may change over time; a change never affects a purchase you have already completed. We never see, receive or store your payment details.

5.5) Restoring your purchase

We do not operate a purchase server. Your Pro entitlement is recorded on your device, which is why it keeps working offline. If you reinstall the App, clear its data, or move to a new device and Pro is not already active, tap Restore purchase— in Settings, or on the purchase screen — while signed in to the same store account that made the purchase.

Because there is no account system, restoring through the store is the only way to recover an entitlement: we cannot grant one ourselves. One behaviour is worth stating plainly. If the store repeatedly reports that your account does not own the purchase, the App stops honouring the entitlement recorded on your device. Tapping Restore purchase while signed in to the account that bought it reinstates it.

5.6) Cancellations and refunds

Refunds are handled by the store you bought from, under that store's refund policy. We are not able to issue them. On Google Play, a purchase that the App does not acknowledge within three days is refunded automatically by Google.

If something has gone wrong with a purchase, email us anyway — we will help where we can, even though the refund decision itself belongs to the store.

6. Advertising in the free version

The free version of CubeXpert is supported by advertising served by Google AdMob. Where ads are enabled, they appear as:

• a full-screen ad shown occasionally after viewing a solution in the Solver;
• an optional rewarded ad you can choose to watch to unlock unlimited hints for a puzzle;
• an ad card in the Lessons list.

Purchasing CubeXpert Pro removes all of them immediately, without restarting the App. Rewarded ads are always opt-in: nothing in the App is reachable only by watching one.

We do not control the content of third-party ads. You can limit ad personalisation in your device settings (on Android, Settings → Google → Ads). For what is shared with advertising partners, see our Privacy Policy.

7. Your data, and where it lives

CubeXpert has no accounts, and we do not run a server that stores anything about you. Your sessions, solves, scrambles, statistics, saved analyses, lesson progress, practice results and settings are written to the App's own storage area on your device rather than to any server of ours. Camera frames used by the scanner are processed on-device in real time; they are not stored and not transmitted.

Two different things get confused here, so we will state them apart. We never receive your data. There is no cloud sync of ours, no account, and no copy on any server we run — which also means we cannot restore, recover or delete your history for you, because we have never held it.

Your own device, however, may back it up for you. Android copies app data to the device owner's Google account by default, and CubeXpert takes part in this: Android Auto Backup can copy your solve history, statistics, saved analyses and settings into your own Google account, and restore them when you reinstall the App or set up a new device. Such a backup belongs to you and to Google, is governed by Google's terms rather than these, and is not something we can read.

This backup is best-effort and is not a backup service. Android performs it only under its own conditions, keeps only the most recent copy, and may never perform it at all; it is applied when the App is installed, not when you clear its data. You can switch it off, or delete what it holds, under Settings → Google → Backup on your device.

So uninstalling the App, or clearing its data, removes your solve history and statistics from this device. Whether they come back afterwards depends entirely on whether a backup of your own exists and is applied — never on anything we hold. If your history matters to you, check that your device's backup is switched on: it is the only copy that can survive a lost or wiped phone.

You are in control of what is written: Settings lets you switch the Solve Analyzer off so no further reports are saved, and delete every report already stored on your device. Deleting them does not give back deep analyses already used in the current window, though that window expires on its own — see 5.3.

What is and is not shared with third parties is set out in our Privacy Policy.

8. Solve Analyzer: a coaching aid, not a verdict

The Solve Analyzer works out which method you used, and where each phase began and ended, by examining the state of the cube after every move. It is a coaching aid. It is not, and cannot be, a perfect record of what you intended.

Different methods pass through identical cube states — a completed ZZ pair is also a Roux block pair, and an oriented Petrus axis is also a ZZ line — so where two methods explain the same solve equally well, the App must choose between readings that the cube itself does not distinguish. Method attribution, confidence scores, phase splits and case recognition are therefore best-effort, and timings, move counts and statistics are provided for your own practice.

Please do not treat the App's output as an official record, and do not use it to settle a competition result.

9. Acceptable use

Use CubeXpert for practice, learning and enjoyment. Please do not:

• use it during an event or competition whose rules prohibit outside assistance;
• interfere with the App, with other people's devices, or with our advertising and billing partners;
• send unlawful, abusive or deliberately misleading content through the feedback address.

10. Third-party software and attribution

CubeXpert is built on open-source work by other people. We are grateful to them, and their licences continue to apply to their code:

• rubiks-vision (MIT) — the camera scanner is a port of it, and the bundled cube-pose model is taken from it unmodified.
• Cube-Solver (BSD 3-Clause) — the CFOP solving plan.
• Beginner solver and ckociemba — the Beginner and Kociemba solving plans.
• Frameworks and SDKs — Flutter, the Google Mobile Ads SDK, ONNX Runtime and OpenCV.

The complete notices are reproduced verbatim on our Open-Source Licences page, and ship inside the App under Settings → About → Acknowledgements.

If you believe something in the App is used without proper attribution, please tell us and we will correct it.

11. Trademarks

Rubik's Cube® and Rubik's® are registered trademarks of their respective owners. CubeXpert is an independent application: it is not affiliated with, authorised by, endorsed by or sponsored by the owners of those marks, and any reference to the puzzle is descriptive only.

Google Play and Android are trademarks of Google LLC. Apple and App Store are trademarks of Apple Inc. CubeXpert and VisionFlutter are ours.

12. Disclaimers and limitation of liability

The App is provided “as is” and “as available”, without warranties of any kind, whether express or implied, including any implied warranties of merchantability, fitness for a particular purpose and non-infringement. We do not warrant that the App will be uninterrupted or error-free, that solutions, hints, analyses or statistics will be accurate or suitable for your purposes, or that defects will be corrected.

To the fullest extent permitted by law, we will not be liable for any indirect, incidental, special or consequential damages, nor for any loss of solve history, statistics or practice progress. Where liability cannot be excluded, our total liability to you for all claims relating to the App is limited to the amount you actually paid for it — for most people that is the price of CubeXpert Pro, or nothing at all.

Nothing in these Terms limits or excludes any right you have as a consumer that cannot be limited or excluded under the law that applies to you.

13. Changes, and ending your licence

We may update the App, add features, and change or discontinue existing ones. If we make a material change to these Terms, we will update the effective date at the top of this page; continuing to use the App after that means you accept the updated Terms.

You may end this licence at any time by uninstalling the App. We may end it if you materially breach these Terms. Ending the licence does not by itself entitle you to a refund — refunds remain the store's decision, as described in section 5.6. A completed CubeXpert Pro purchase continues to apply to the App as we distribute it.

14. Questions, disputes and contact

We would much rather hear from you than leave you stuck. If you have a question about these Terms, a problem with a purchase, or an attribution correction, email us first and we will do our best to resolve it informally.

Purchases made through Google Play also remain subject to Google Play's terms and dispute processes.