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Terms of Service

Last Updated: November 3, 2026

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These Terms of Service govern your access to and use of ChessRank.org, its free Stockfish game analysis tools, puzzles, and features.

1. Agreement to Terms

These Terms of Service ("Terms") are a binding agreement between you and Matěj Štaif, an individual based in the Czech Republic, who operates ChessRank.org (the "Platform") and who is referred to in these Terms as "we", "us" or "our". By accessing or using the Platform, you agree to be bound by these Terms and by our Privacy Policy. If you do not agree with any part of these Terms, you must stop using the Platform immediately.

When you create an account, you accept these Terms expressly. These Terms apply to guests and registered users alike, and to every part of the Platform, including its subdomains, the emails we send and the images the Platform generates for sharing.

2. Description of Service

ChessRank.org is an independent online chess training and analysis platform created by Matěj Štaif. The Platform provides web-based tools including, but not limited to:

All core functionality is provided free of charge without mandatory subscription paywalls or artificial daily analysis limits.

Who is behind it. ChessRank.org is run by one person, Matěj Štaif, a student of Artificial Intelligence at FIT CTU in Prague. He took up chess in March 2026 to beat his father, built the first version as a personal tool to learn from his own mistakes and opened it to the public on 1 July 2026. There is no company, investor or advertiser behind the Platform, and every bug report or suggestion reaches him directly. The full story is on the Behind ChessRank.org page.

3. Account Registration, Communications & Local Storage

You can use most tools on ChessRank.org without creating an account. Preferences, themes, and guest progression are stored locally in your browser’s localStorage.

If you create a registered user account, either with an email address and password or by signing in with Google or Apple (authentication is provided by Supabase), you are responsible for maintaining the confidentiality of your login credentials and for all activities under your account. You can manage or delete your account at any time in Settings.

We dislike spam as much as you do. Where permitted by applicable law, we only send occasional and relevant product emails about ChessRank.org features and important product updates. You can opt out at any time in Settings, using the unsubscribe link in any product email, or by contacting [email protected]. Once you opt out, we will not send you further product emails.

Product email preferences do not affect service messages needed to operate or secure your account, such as email verification, password resets, security notices, or notices about material changes to the Platform or these Terms.

4. Acceptable Use & Fair Play

You agree to use ChessRank.org responsibly and solely for lawful purposes. Specifically, you agree NOT to:

  • Cheating in Live Games: Use ChessRank.org’s real-time engine evaluation or calculation tools to assist yourself during active, live competitive games on third-party platforms (such as Chess.com or Lichess) where live engine assistance is strictly forbidden. We fully support fair play and anti-cheating policies in online chess.
  • Automated Scraping & Abuse: Perform automated scraping, bot attacks, denial-of-service (DDoS) attempts, or excess API polling that degrades service stability for other players.
  • Security Violations: Attempt to reverse-engineer server infrastructure, bypass security controls, or inject malicious code into the Platform.
  • Usernames, Avatars & Feedback: Choose a username, display name or avatar, or submit feedback or attachments, that is offensive, hateful, sexually explicit, misleading, impersonates another person or organisation, or infringes the rights of others. We may rename, reset, hide or remove such content without prior notice.
  • Leaderboard & Rating Manipulation: Use chess engines, scripts, multiple accounts or any other unfair means to manipulate puzzle ratings, streaks, leaderboards, leagues or other statistics.
  • Access Outside the Interface: Access or call the Platform's APIs, endpoints or data feeds other than through the Platform's own user interface, or circumvent, disable or interfere with rate limits, access controls or any other technical measures that protect the Platform or its content.
  • Account Misuse: Create accounts by automated means, or sell, rent, transfer or share your account with anyone else.

Usage limits. Some features, such as Opponent Prep, are very demanding on our servers and expensive to run. To keep them available to everyone, we apply usage limits. We do not publish these limits and may change them at any time. When they are exceeded, access to the feature may be paused automatically for a period of time, and repeated excess may lead to a longer pause. We're sorry for any inconvenience this causes. If you believe a pause was a mistake, write to [email protected] with the code shown on the screen.

Reporting. If you believe that content on the Platform, such as a username, avatar or profile, is illegal or infringes your rights, please report it to [email protected] with a link to the content and a short explanation. We review every report, and when we remove or restrict content or an account, we tell the affected user why, unless the law prevents it.

5. Third-Party Integrations & Compatibility Notice

ChessRank.org allows players to import public PGN games and stats from platforms such as Chess.com and Lichess.

Disclaimer: ChessRank.org is an independent platform and is not officially affiliated with, endorsed by, or sponsored by Chess.com or Lichess. All third-party trademarks and brand names belong to their respective copyright holders. Public game fetching is conducted via official public developer APIs.

These imports are requested directly by your browser from the official public APIs of those platforms. Your use of Chess.com and Lichess remains subject to their own terms and privacy policies, and we are not responsible for the availability, accuracy or content of the data they provide.

6. Intellectual Property, Trademarks & Open-Source Software

The Stockfish chess engine used on ChessRank.org is open-source software licensed under the GNU General Public License v3 (GPLv3). In compliance with GPLv3, source attribution, license references and links to the corresponding source code are provided on our Credits & licenses page, together with the notices for all other third-party open-source components and assets used on the Platform.

ChessRank.org is created and operated by Matěj Štaif, an individual based in the Czech Republic. All original platform designs, source code, UI graphics, animations, layout components and branding for ChessRank.org are the intellectual property of Matěj Štaif. Wherever this section refers to our rights, it means the rights of Matěj Štaif.

All rights reserved. Except for the third-party components listed on the Credits & licenses page, which remain subject to their own licenses, all content of the Platform is protected by copyright and other intellectual property laws, including the Czech Copyright Act (Act No. 121/2000 Coll.) and the sui generis database right under EU law, as well as international copyright treaties such as the Berne Convention, under which it is protected in almost every country in the world. This includes, without limitation: the source code and the compiled client-side code (JavaScript, CSS and WebAssembly glue code), the visual design, layouts and UI components, the overall look and feel of the Platform, icons, illustrations and graphics, all animations and motion design, the Chess Coach character with its artwork, animations and voice lines, every text that Chess Coach says or shows (including move comments, hints, explanations and chess facts) in all languages, the original bot characters with their names, artwork and personalities, the images the Platform generates for sharing (such as share cards), the email templates, all texts and translations, the evaluation, accuracy, rating and move-classification models and their parameters, the opening book and other databases, as well as the ChessRank.org name and logo.

Trademarks. ChessRank, ChessRank.org, the ChessRank.org logo and the Chess Coach character, including its appearance, artwork and animations, are trademarks and distinctive signs of Matěj Štaif, whether registered or not. Without our prior written permission, you may not use them, or any name, logo or character that could be confused with them, in the name of a website, app, domain or social media account, in advertising or as advertising keywords, or in any other way that suggests that you or your product is affiliated with, endorsed or sponsored by ChessRank.org. You may still mention ChessRank.org by name to refer to it truthfully, for example in a review or an article.

Limited license. We grant you a personal, revocable, non-exclusive and non-transferable license to access and use the Platform in your web browser for your own non-commercial chess training. No other right is granted to you, whether expressly, by implication or otherwise. The fact that code, graphics or data are delivered to your device and executed in your browser does not give you any right to copy, reuse or redistribute them.

Without our prior written permission, you may NOT:

  • Copy, download, reproduce, modify, translate, adapt or create derivative works of any part of the Platform, including its code, design, graphics, animations, texts or data.
  • Decompile, de-minify, deobfuscate, disassemble or otherwise reverse-engineer the Platform's client-side or server-side code, or extract its models, algorithms, parameters or databases, except to the extent that mandatory law expressly permits it.
  • Scrape, crawl or systematically extract content or data from the Platform, whether by automated means or manually, including with the help of AI agents or large language models.
  • Use any part of the Platform, its content or its outputs to train, fine-tune or evaluate machine-learning or AI models, or to build, improve or benchmark a competing product or service.
  • Republish, sell, sublicense, frame, mirror or otherwise make any part of the Platform available on another website, app or service.
  • Remove, hide or alter any copyright, trademark or license notice.

What you may do. You may share links to the Platform, share the images the Platform generates for sharing (such as share cards), quote short excerpts with clear attribution and a link to ChessRank.org, and copy the text of these legal pages (for example with the copy button at the top of the page) to read, save or have it explained for your own personal use. Third-party open-source components may be used under the terms of their own licenses, as listed on the Credits & licenses page.

Search engines and AI assistants. Search engines and AI assistants may crawl and read the publicly accessible pages of the Platform as allowed by our robots.txt, for example the Behind ChessRank.org page, the blog and these legal pages, in order to index them, link to them and quote or summarise them with a reference to ChessRank.org. This permission does not cover training or fine-tuning AI models, building a competing product, or reproducing substantial parts of the Platform.

Your content. You keep the rights you have in the content you add to the Platform, such as your username, display name, avatar, custom puzzles, the PGN games you save and the Chess.com and Lichess usernames you link to your account. You grant us a worldwide, non-exclusive, royalty-free license to host, store, copy, display and adapt that content (for example to resize an avatar) as far as needed to operate and show the Platform, including on public profiles, leaderboards and share images. You may link only Chess.com and Lichess accounts that are your own, and you confirm that you have the right to grant this license. The license ends when you delete the content or your account, except where the law requires us to keep it.

Feedback and ideas. If you send us feedback, suggestions, ideas or bug reports, through the feedback form or in any other way, you agree that we may use, implement, modify and publish them freely, worldwide, without any obligation or compensation to you. Sending feedback does not give you any right to the Platform or to any feature built with its help.

Enforcement. Any use that breaches this section infringes our rights and is a material breach of these Terms. We may suspend or terminate your access and pursue every remedy available under applicable law, including injunctive relief, the removal and destruction of infringing copies, and compensation for damages and unjust enrichment.

Survival. This section continues to apply after you stop using the Platform or delete your account.

7. Disclaimer of Warranties

THE PLATFORM AND ALL INCLUDED TOOLS, ENGINE EVALUATIONS, AND ANALYSIS RESULTS ARE PROVIDED ON AN "AS IS" AND "AS AVAILABLE" BASIS WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED. WHILE WE STRIVE FOR 100% RELIABILITY AND ACCURACY, WE DO NOT GUARANTEE THAT THE PLATFORM WILL BE UNINTERRUPTED, SECURE, OR ERROR-FREE AT ALL TIMES.

Changes to the Platform. We may add, change, suspend or discontinue any part of the Platform at any time, temporarily or permanently. Engine evaluations, accuracy scores, ratings and move classifications are estimates for chess training only and may differ from the results of other tools. Nothing in this section limits the rights you have as a consumer that cannot be excluded by law.

Saved data. The Platform is not a backup service. For a valid reason, such as the cost, security or stability of the Platform, we may change at any time what content and data we keep for you, how much of it and for how long, including any limits stated elsewhere on the Platform. Where reasonably possible, we will tell you in advance. Saved content and data may also be lost, for example because of a technical failure or an outage at one of our providers, so please keep your own copy of anything that matters to you. To the extent permitted by law, we are not liable for the loss or deletion of saved content or data.

Chess Coach. The comments, hints, explanations and chess facts that Chess Coach says or shows are generated automatically from engine analysis. They are meant for chess training and entertainment, may be inaccurate or incomplete, and are not professional advice.

8. Limitation of Liability

TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, CHESSRANK.ORG AND ITS DEVELOPER (MATĚJ ŠTAIF) SHALL NOT BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, OR PUNITIVE DAMAGES ARISING OUT OF OR IN CONNECTION WITH YOUR USE OF OR INABILITY TO USE THE PLATFORM.

Mandatory law. Nothing in these Terms excludes or limits liability that cannot be excluded or limited under applicable law, in particular liability for harm caused intentionally or through gross negligence, or for harm to a person's life, health or other natural rights. Where the law permits a limitation, our total liability to you is limited to the greater of two amounts: the amount you paid us in the twelve months before the claim arose, or 50 euros.

Your responsibility. You are responsible for any loss or damage we suffer because you breached these Terms or the law, including the reasonable costs of enforcing our rights, to the extent permitted by applicable law.

9. Eligibility & Age Requirement

ChessRank.org is open to players of all ages, and the tools can be used without an account. To create a registered account you must be at least 13 years old, or at least 16 in jurisdictions where that is the minimum age for consent to information society services. If you are under the applicable age, you may use the Platform only with the involvement of a parent or guardian.

10. Suspension & Termination

You may stop using the Platform and delete your account at any time in Settings. We may suspend, restrict or remove an account, or block access to the Platform, if these Terms are breached, in particular sections 4 and 6, if a public leaderboard is manipulated, or if the stability or security of the Platform or its users is put at risk. We may also stop providing the service to a registered account for any other reason by giving reasonable notice in advance. When we restrict or remove an account, we tell the user why, unless the law prevents it or it would put the security of the Platform at risk. Sections 6, 7, 8 and 12, and every other provision that by its nature should continue, remain in force after an account ends.

11. Voluntary Donations

ChessRank.org is free. If you choose to support the project financially, the payment is processed on Stripe’s hosted checkout under Stripe’s own terms, and we never receive or store your card details. Donations are voluntary, buy no additional features, and are non-refundable except where the law requires otherwise.

12. Governing Law, Severability & General Provisions

These Terms are governed by the laws of the Czech Republic, without regard to conflict-of-law rules, and the courts of the Czech Republic have jurisdiction over any dispute arising from them. If you are a consumer resident in the European Union, this does not deprive you of the protection of the mandatory consumer law of your own country, or of your right to bring proceedings there.

If any provision of these Terms is held invalid or unenforceable, the remaining provisions stay in full force, and the invalid provision is replaced by a valid one that comes closest to its original intent.

Transfer. We may transfer these Terms, the Platform and all related rights and obligations to a successor, for example to a company controlled by Matěj Štaif or to a buyer of the Platform. Such a transfer does not reduce your rights as a user. You may not transfer your rights or obligations under these Terms without our prior written consent.

No waiver. If we do not enforce a provision of these Terms immediately or in a particular case, we do not give up our right to enforce it later or in any other case.

Entire agreement and language. These Terms and the Privacy Policy form the entire agreement between you and us about the Platform. The Terms are written in English. Translations are provided for convenience, and if a translation differs from the English version, the English version prevails to the extent permitted by law.

13. Changes to These Terms

We may change these Terms for a valid reason, in particular because of a change in the law or in the requirements of a court or authority, to reflect new, changed or discontinued features, to protect the security of the Platform and its users or to prevent abuse, because of changes in the third-party services we rely on, because the Platform is transferred to a successor, or to clarify wording or correct errors.

How we tell you. Every version of these Terms shows the date from which it applies. If a change is material, we will inform registered users at least 14 days before it takes effect, by email to the address associated with the account or by a clear notice on the Platform. Changes that are required by law, that respond to a security threat, that only concern new features or that are solely to your benefit may take effect immediately.

Your choice. If you do not agree with a change, you can delete your account in Settings free of charge at any time before the change takes effect, and stop using the Platform. If you keep using the Platform or your account after the change has taken effect, the new version of these Terms applies to you, including to your existing account and to the content you added before the change.

No retroactive effect. A change applies only from its effective date. Events that happened before that date remain governed by the version of these Terms that was in force at the time. Earlier versions are available on request at [email protected].

14. Contact & Questions

If you have any questions or feedback regarding these Terms of Service, please contact us via email at [email protected] or visit our Behind ChessRank.org page.

ChessRank.org is an independent project and is not affiliated with, endorsed or sponsored by Chess.com, Inc., Lichess or Stockfish. All trademarks are the property of their respective owners.