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Terms of Service

Please read these Terms carefully before using NOTE-KU. By using the app or the website, you agree to them. If you do not agree, do not use NOTE-KU.

Effective: May 31, 2026 · Last updated: October 28, 2026

1. Acceptance of Terms

These Terms of Service (“Terms”) constitute a legally binding agreement between you (“User”) and NOTE-KU (“we”, “us”, “our”) governing your use of the NOTE-KU app, the website at noteku.app, and associated digital products including books, puzzle packs and educational content (collectively, the “Service”).

By using the Service you represent that you are at least 4 years of age, or that you are using the Service with parental consent and supervision.

2. Description of Service

NOTE-KU is a sudoku application built around a proprietary solving methodology (the “NOTE-KU Method”) using systematic candidate notation. The Service includes:

  • The NOTE-KU app — free to use in your web browser
  • An in-app store with cosmetic items obtainable with NoteCoins
  • The NOTE-KU website at noteku.app
  • Digital books and puzzle packs describing and practising the NOTE-KU Method

All five difficulty levels and both game modes are free. The in-app store offers cosmetic items only and does not affect gameplay.

3. Intellectual Property

3.1 Our Content

The NOTE-KU name, logo, brand identity, application code, visual design, the NOTE-KU Method (including the Three-Phase system, Two-Candidate Rule, Temp Mode, and Final Pass mechanic), all written content, and all books and puzzle packs are the exclusive intellectual property of NOTE-KU, protected by copyright, trademark, and applicable laws.

You may not copy, reproduce, distribute, modify, create derivative works from, or commercially exploit any part of the Service without our express written permission.

3.2 Your License

We grant you a limited, non-exclusive, non-transferable, revocable license to use the app on your personal devices for personal, non-commercial entertainment and educational purposes. This license does not include the right to:

  • Distribute or resell the app or any part of it
  • Reverse engineer, decompile, or extract the app’s source code
  • Use the NOTE-KU name or branding in any public context without permission
  • Train artificial intelligence or machine learning models on our content

4. NoteCoins Virtual Currency

NoteCoins are a virtual in-app currency with no real-world monetary value. They cannot be:

  • Purchased with real money in the current version of the app
  • Transferred between users
  • Redeemed for cash or real-world goods
  • Refunded once spent in the store

NoteCoins are earned by completing puzzles (Beginner through Extreme, and your own puzzles). Mini (6×6) puzzles are for practice and do not earn NoteCoins. We reserve the right to modify earn rates, store prices, and available items at any time.

5. Acceptable Use

You agree not to:

  • Exploit bugs or vulnerabilities to earn NoteCoins artificially
  • Use automated tools, scripts, or bots to interact with the app
  • Use the Service for any commercial purpose without written permission
  • Impersonate NOTE-KU or claim affiliation with us

6. Digital Products and Purchases

6.1 License

Digital books and puzzle packs are delivered as PDF files and licensed for personal use only. Your license is personal, non-transferable, and limited to personal educational use. It does not include the right to reproduce, distribute, or teach from the material commercially.

6.2 Refund Policy

Due to the digital nature of our products, all sales are final. If you experience a technical issue preventing download or access, contact us at contact@note-ku.com within 30 days of purchase and we will resolve the issue or provide a replacement file.

7. Disclaimer of Warranties

THE SERVICE IS PROVIDED “AS IS” WITHOUT WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED. TO THE FULLEST EXTENT PERMITTED BY LAW, NOTE-KU DISCLAIMS ALL WARRANTIES INCLUDING IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. We do not warrant that the app will be error-free or uninterrupted.

8. Limitation of Liability

TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, NOTE-KU SHALL NOT BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, OR PUNITIVE DAMAGES ARISING FROM YOUR USE OF THE SERVICE. Our total liability shall not exceed the amount you have paid us in the preceding 12 months, or USD $10, whichever is greater.

9. Modifications to the Service

We reserve the right to modify, suspend, or discontinue any part of the Service at any time. We may add or remove themes, adjust NoteCoin rates, update gameplay features, or change the interface. We will make reasonable efforts to notify users of significant changes.

10. Governing Law

These Terms are governed by the laws of Argentina. For EU users, mandatory consumer protection laws of your country of residence also apply. Disputes shall first be attempted through good-faith negotiation (contact contact@note-ku.com), and if unresolved, submitted to the competent courts of Argentina unless applicable law requires otherwise.

11. Changes to These Terms

We may update these Terms from time to time. Material changes will be posted on this page with an updated date. Continued use of the Service after changes take effect constitutes your acceptance of the revised Terms.

12. Contact

For questions about these Terms: contact@note-ku.com · noteku.app