Terms and Conditions

Last updated: 19 October 2026  ·  Effective date: 19 October 2026  ·  Version 1.3

1. About these Terms

These Terms and Conditions (the "Terms") form a legally binding agreement between you ("you", "the User") and Yevhenii Chebotarkyi, an individual operating Ochess as a personal project, based in the United Kingdom (the "Service Operator", "we", "us").

Contact: support@ochess.app

The Terms govern your use of the Ochess website (currently hosted at ochess.app), the Ochess app for iPhone distributed through Apple's App Store, the Ochess app for Android distributed through Google Play (together, the "Apps"), and any related subdomains and servers operated by us (together, the "Service"). They apply whether you use the Service with an account or as a guest without one. Some features, such as direct messages and public labs, are currently available only on the website.

The iPhone App is distributed on the App Store from a developer account held by a member of our family, on our behalf and under a licence from us, so the seller name the App Store shows may differ from the name above. We remain responsible for the Apps and the Service under these Terms. Your licence to use an App downloaded from the App Store itself is governed by Apple's standard Licensed Application End User License Agreement; these Terms govern your Ochess account and the Service you reach through the App.

By creating an account, ticking the agreement box, or otherwise using the Service, you confirm that you have read, understood, and agreed to these Terms and to our Privacy Policy. If you do not agree, do not use the Service.

2. About the Service

Ochess is a chess training tool that allows registered users to:

• Create and study opening labs (move trees with chapters, notes, and training drills)
• Import their games from Lichess, Chess.com, or in PGN format
• Look up opening statistics via Lichess Opening Explorer
• Analyse positions and games with the Stockfish chess engine
• Send direct messages to other registered users
• Share labs publicly, by unlisted link, or keep them private

The Service is currently free of charge and under active development. We may introduce paid features in the future; if and when we do, we will update these Terms and notify registered users.

3. Eligibility and account registration

3.1 Age

Anyone may use the Service without an account. To create an account you must be at least 13 years old. If you are under 18, or under the age at which you can agree to these Terms yourself where you live, you may create and use an account only with the permission of a parent or guardian, who accepts these Terms on your behalf. By registering, you confirm that this is the case.

We close an account if we learn that its holder is under 13. A parent or guardian can ask us to close their child's account at any time by writing to support@ochess.app.

3.2 Account creation

You can register using:

• An email address and password
• A Google account (via Google OAuth)
• An Apple Account (Sign in with Apple), in the iPhone App

After registration, you must choose a unique username (minimum 3 characters). Usernames must not be offensive, impersonate another person or organisation, or violate the rights of any third party. We reserve the right to reclaim usernames at our discretion if they breach these rules.

3.3 Accuracy and security

You agree to provide accurate information. You are responsible for keeping your password secure and for all activity on your account. If you suspect your account has been compromised, contact us immediately at support@ochess.app.

You may have only one account, unless we explicitly agree otherwise in writing.

4. Acceptable use

You agree not to:

1. use the Service for any unlawful purpose or in violation of any applicable law;
2. harass, threaten, defame, or impersonate any other person, including other users or the Service Operator;
3. post, share, or transmit content that is hateful, discriminatory, sexually explicit, violent, or otherwise inappropriate;
4. post, share, or transmit content that infringes any third party's intellectual property, privacy, or other rights;
5. use the Service to send spam, unsolicited messages, or commercial promotion of any kind;
6. attempt to gain unauthorised access to other users' accounts or to non-public areas of the Service;
7. interfere with the operation of the Service, including by uploading malicious code, exploiting bugs, or making excessive automated requests;
8. scrape, harvest, or mass-download data from the Service except where explicitly permitted (e.g. exporting your own data via the API where provided);
9. reverse-engineer, decompile, or attempt to extract the source code of the Service beyond what is permitted by applicable law;
10. use the Service to facilitate cheating in chess games on any platform (this includes using imported analysis to cheat in real-time games elsewhere).

Violation of these rules may result in warnings, content removal, account suspension, or permanent account closure, at our sole discretion. We will try to act reasonably, and you can ask us to look at a decision again (see section 5.6).

5. Your content

5.1 Ownership

You retain ownership of all content you create on the Service, including opening labs, notes, comments, direct messages, and any text or data you upload (collectively, "Your Content").

5.2 Licence to us

To operate the Service, you grant us a non-exclusive, worldwide, royalty-free licence to host, store, copy, transmit, and display Your Content solely for the purpose of providing the Service to you and to other users you choose to share with. This licence ends when you delete the relevant content or your account, except for residual copies in backups, which expire as described in our Privacy Policy.

5.3 Public and shared content

If you choose to make a lab "public" or share it via an "unlisted" link, you grant any user who accesses it the right to view and study its content. If a lab is set to public, it may be discoverable through the Service's interface; if unlisted, it is accessible only via the share link, but anyone with that link can pass it on.

You are solely responsible for what you choose to make public or share.

5.4 Direct messages

Direct messages are visible to the recipient. When someone writes to you for the first time, their message arrives as a request: you see who wants to write to you, not what they wrote, until you accept it, and you can decline or report it instead. Messages from the Service Operator arrive directly.

The Service Operator does not routinely read messages. We read a conversation when one of its participants reports it, and can technically access messages for security, abuse-handling, or legal compliance purposes. Do not send anything through Ochess messages that you would not want a third party to read.

5.5 Removal of content

We may remove any content that, in our reasonable judgement, breaches these Terms or applicable law, without prior notice.

5.6 Reports and complaints

You can report a conversation, a comment, a shared lab or a public lab with the Report button next to it. If you have no account, or want to tell us about anything else on the Service, email support@ochess.app.

We review every report. We remove content that is illegal or breaks these Terms, and we may warn, suspend or close the account responsible. If you think we removed your content or restricted your account by mistake, or that we did not act on a report as we should have, email us and we will look at it again and reply.

6. Imported and third-party data

6.1 Games imported from Lichess and Chess.com

When you import games, the chess data (moves, results, metadata) originates from those platforms and remains subject to their respective terms. We process it solely to display, store, and analyse it within your account.

6.2 Opening database

The opening database used by the Service is derived from publicly available chess game data published by Lichess (lichess.org) under the Creative Commons CC0 licence. Source: github.com/lichess-org/chess-openings.

6.3 Lichess Opening Explorer

Opening statistics in a lab are served through our own caching proxy (api.ochess.app), which fetches data from the Lichess Opening Explorer API (explorer.lichess.ovh) on the server side. This underlying data is governed by Lichess's terms of use.

6.4 Stockfish

The Service uses Stockfish, an open-source chess engine licensed under the GNU General Public License v3. When you explore a position on the website, Stockfish runs locally in your browser; we do not modify it, and the npm package source is available on npmjs.com/package/stockfish. Full game analysis on the website, and all engine analysis in the Apps, runs on our own server (api.ochess.app).

6.5 Maia

Game analysis uses Maia-2, a human-like chess model developed by the Maia Chess team at the Computational Social Science Lab, University of Toronto. Maia-2 is released under the MIT License (Copyright © 2024 CSSLab), available at github.com/CSSLab/maia2. We run the published model converted to the ONNX format for inference; the network's weights are unchanged.

6.6 Fonts

The Service uses the fonts Cormorant Garamond (Copyright © 2015 the Cormorant Project Authors) and IBM Plex Mono (Copyright © 2017 IBM Corp., with Reserved Font Name "Plex"), which we host ourselves. Both are licensed under the SIL Open Font License 1.1.

6.7 Chess pieces

The chess pieces shown on the boards of the Service, including the Apps, are the "cburnett" set, created by Colin M.L. Burnett (Wikimedia Commons user Cburnett) and contributors, and published on Wikimedia Commons. The author offers them under several licences; we use them under the BSD 3-Clause License, reproduced below. The author does not endorse Ochess.

Copyright © 2006 Colin M.L. Burnett (Wikimedia Commons user Cburnett) and contributors

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. Neither the name of Colin M.L. Burnett nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY COLIN M.L. BURNETT AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COLIN M.L. BURNETT AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

7. Our intellectual property

The Service's source code, design, layout, original graphics, trademarks (including the name "Ochess" and any logos), and original content are owned by us and are protected by copyright, trademark, and other applicable laws. Third-party materials used by the Service, including the chess piece graphics, fonts, the Stockfish engine, the Maia model and the data listed in section 6, belong to their respective authors and are used under the licences or terms stated there; nothing in these Terms limits any rights you have under those licences. These Terms do not grant you any right to use our own materials other than as necessary for normal use of the Service as a registered user.

8. Privacy

Your privacy is important to us. Please read our Privacy Policy to understand what personal data we collect, why, and how we handle it. By using the Service, you also agree to the practices described in the Privacy Policy.

9. Service availability

The Service is provided "as is" and "as available". We do not guarantee that:

• the Service will always be available, uninterrupted, or error-free;
• the Service will meet your specific requirements;
• any data you upload will be permanently retained or never lost.

We may modify, suspend, or discontinue any feature or the entire Service at any time, with or without notice. As Ochess is a personal project under active development, we reserve broad discretion here.

You are responsible for maintaining your own backups of any content important to you.

10. Account termination

10.1 By you

You may delete your account at any time: on the website from your profile page, in the Apps under Account → Delete account, or by email without signing in, as described on the account deletion page. Deletion erases your profile, username reservation, imported games, training progress, opening labs (private, public, and shared), Cloud Storage files associated with your labs, all your direct messages, and the reports you made or that were made about your account. See the Privacy Policy for what remains in backups and for how long.

10.2 By us

We may suspend or terminate your account, without notice, if:

• you breach these Terms;
• we are required to do so by law;
• the Service is being discontinued.

In the event the Service is discontinued, we will use reasonable efforts to give registered users at least 30 days' notice and a chance to export their data.

11. Disclaimers and limitation of liability

11.1 Disclaimer

Except as expressly stated in these Terms or required by applicable law, the Service is provided without any warranties or conditions of any kind, whether express or implied. To the maximum extent permitted by law, we disclaim all warranties, including warranties of merchantability, fitness for a particular purpose, accuracy, and non-infringement.

11.2 Limitation of liability

To the maximum extent permitted by law, we will not be liable for:

1. any indirect, incidental, consequential, special, or punitive damages;
2. any loss of data, profits, revenue, business, or goodwill;
3. any inability to access or use the Service;
4. any actions or content of other users;
5. any reliance you place on opening statistics, Stockfish evaluations, or other information provided by the Service.

If, despite the above, we are found to be liable, our total aggregate liability to you in connection with the Service is limited to £100 or the amount you have paid us in the previous 12 months, whichever is greater. As the Service is currently free, this means our liability is capped at £100.

11.3 What we don't disclaim

Nothing in these Terms excludes or limits our liability for:

• death or personal injury caused by our negligence;
• fraud or fraudulent misrepresentation;
• any other liability that cannot be excluded under English law.

12. Indemnity

You agree to indemnify and hold us harmless from any claim, loss, damage, liability, or expense (including reasonable legal fees) arising from your breach of these Terms, your misuse of the Service, or your infringement of any third party's rights.

13. Changes to these Terms

We may update these Terms from time to time. The "Last updated" date at the top reflects the latest revision.

For material changes, we will notify registered users by email and/or through the Service before the changes take effect. If you do not accept the updated Terms, you may delete your account; continued use after the effective date of the new Terms means you accept them.

14. Miscellaneous

14.1 Governing law

These Terms are governed by the laws of England and Wales.

14.2 Jurisdiction

Any dispute arising out of or in connection with these Terms is subject to the exclusive jurisdiction of the courts of England and Wales, except that, if you are a consumer in the EEA or another jurisdiction with overriding consumer protection rules, you may also have the right to bring proceedings in your country of residence.

14.3 Severability

If any provision of these Terms is found to be invalid or unenforceable, the remaining provisions will continue in full force.

14.4 No waiver

Our failure to enforce any right or provision of these Terms is not a waiver of that right or provision.

14.5 Entire agreement

These Terms, together with the Privacy Policy, constitute the entire agreement between you and us regarding the Service, and supersede any prior agreements. Nothing in them replaces or limits Apple's standard Licensed Application End User License Agreement as it applies to your licence of the iPhone App.

14.6 Assignment

You may not assign or transfer these Terms or your account to anyone else. We may assign these Terms (for example, if we move the project to a corporate entity in the future); we will notify you if we do.

14.7 Language

These Terms are provided in English. Any translation we may publish in future is for convenience only, and the English version prevails.

15. Contact

For any questions about these Terms:

Email:support@ochess.app