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Terms of Use

The rules, rights and responsibilities that apply when you use TheoryChess.

Last updated: 12 November 2026

Effective date: 1 October 2026
Last updated: 12 November 2026

These terms govern your use of the TheoryChess website and service (the “Service”), run by Hasan Süzen. By using the Service or creating an account you accept these terms. If you do not accept them, please do not use the Service.

1. The Service

TheoryChess is a training tool for learning chess openings by playing against the engine, taking quizzes and reviewing with spaced repetition. The opening catalogue, training, quizzes, spaced repetition and analysis are free. Content, features and scope may change over time; significant changes that affect you directly are announced on the site.

2. Premium, the beta and the free report

  • Premium features: game reports and opponent prep are Premium features.
  • Beta: during the beta, Premium features are free for everyone signed in. The end of the beta is announced on the site in advance.
  • Free report: once the beta is over, every account without Premium can get one free report on its own games. If the report cannot be made (for example, the username is not found), the free report is given back.
  • Getting Premium: Premium cannot be bought yet; an admin may give it for a set period. When paid Premium is offered, the price, payment, right of withdrawal and cancellation terms will be set out separately and clearly before any purchase. Nothing in these terms creates an obligation to pay.
  • Interest in Premium: the “I’m interested in Premium” option only records your interest; it does not lead to any email or other commercial message and can be withdrawn at any time.

3. Game reports and opponent prep

  • Reports are made from games that are public on lichess and Chess.com. Those sites are independent of TheoryChess; making reports depends on their availability and rules. When they are busy or apply request limits, reports are made in turn and may be delayed.
  • In “My game report” you should only type the username of an account that is yours.
  • Opponent prep is for chess preparation only. It may not be used to harass or stalk other players, to build bulk profiles of them, or to publish what you learn in a way that demeans them.
  • Limits: at most 20 reports a day, one report being made at a time, and at most 20 games per report. The latest 10 reports per account are kept, each for at most 90 days.
  • Theory comparisons and engine verdicts are produced automatically and are not promised to be error-free (see section 7).

4. Your account

  • You create an account by signing in with Google. An account can also be made with a username and password through an invite link a coach sends to you personally; this only works with such a link. You are responsible for the security of your account, your password and the linked Google account.
  • Accounts are personal; they may not be transferred or opened on someone else’s behalf.
  • Children under 13 may make an account only through their coach’s invite link, with a parent’s or guardian’s permission, using a username and password. Users under 18 should use the Service with a parent’s or guardian’s permission.

The coach system (beta)

  • Approved coaches can send their students private, single-use invite links. When you accept an invite, that coach sees your opening study, including what you studied before you linked, as listed in the Privacy Policy; they never see your email address, game reports or opponent prep. You can leave a coach at any time, and a coach can remove you from their list.
  • The coach you are linked to can give you assignments and write a one-way note on them. Only you and the coach who gave an assignment see it and its note (TheoryChess may see them only when looking into a complaint or carrying out a data request); whether it is complete is worked out on its own from your study. When the coach deletes an assignment, the coach removes you from their list or you leave the coach, it leaves your list. If a coach’s coaching is suspended, their assignments of catalogue openings stay in your list but their notes are not shown while the suspension lasts. If you see something in a note that is not right, write to us.
  • A coach can assign you an opening they made themselves. Its name, moves and line names are seen only by that coach and the students the coach assigned it to, and by no one else unless a complaint has to be reviewed; you do not see the coach’s notes on moves along the way, and a note on the last move of a line is shown as that line’s name. The opening is not public. Studying a coach’s opening counts towards your study points; its quizzes do not count towards quiz points on the leaderboard. The opening is no longer shown to you if the coach deletes it or the assignment, the coach removes you from their list or you leave the coach. If the coach’s coaching is suspended, the opening and its assignment are not shown to you until the coach is restored (assignments of catalogue openings stay in your list).
  • If you appear on the leaderboards, a “Coach” mark if you are an approved coach, or a “Works with a coach” mark if you are linked to an approved coach, is shown beside your name. Which coach you work with is never shown anywhere public. Accounts made with a username start hidden on the leaderboards; if you do not want to appear there, you can hide yourself in your account settings.
  • An invite link is only for the person it was sent to. Do not use a link that is not yours, and do not pass on a link sent to you.
  • If the password of an account made with a username is forgotten, its owner starts the reset, and the linked coach (or, without an approved one, the operator of the site) approves it by typing in the code the owner reads out from their own screen; the code is shown nowhere else, and five wrong codes end the request. The approval allows a new password to be set through that request; it is a trust placed in the coach. When your password is changed through a reset request, your profile shows the date and whether your coach or the operator of the site approved it; if it was not you, tell your coach or us. Tell this code only to your own coach or to TheoryChess, and never tell anyone your password.
  • To apply as a coach and use the coach features you must also accept the Coach Terms. A parent or guardian who works with their own child can apply through the same form; if approved, they count as a coach. The coach system is free during the beta; its scope and terms may change.

5. Acceptable use

When using the Service you agree not to:

  • use it for unlawful purposes or in a way that infringes others’ rights,
  • try to disrupt it, overload it or get around its security measures,
  • collect data in bulk with automated tools outside the interfaces made available,
  • try to access another user’s account or impersonate someone else,
  • set up schemes to obtain scores or results misleadingly,
  • use several accounts or automated tools to get around report limits or the free report.

User content and reporting it

The display name and profile photo on your account can be seen by others on your profile and, if you turned it on, on the leaderboard. You are responsible for them; you may not use content that insults, infringes someone’s personal rights or intellectual property, impersonates someone or is otherwise unlawful.

You can report content you believe is unlawful to [email protected], with a link to the page it is on and your reasons. As a hosting provider under Turkish Law No. 5651, we review content reported as unlawful and, where justified, remove it as soon as possible; orders from competent authorities are applied at once. Accounts using content against these rules may have their display name changed, be taken off the leaderboard or be suspended under section 9.

6. Intellectual property

The site’s design, text, blog posts and the TheoryChess name and logo belong to Hasan Süzen and may not be copied or used commercially without permission. The open-source components used in the Service (the Stockfish chess engine, the opening dataset, the piece artwork and the 3D model) are subject to their own licences, and nothing in these terms restricts the rights those licences give you. See Licenses and Credits.

7. About the analysis

Move evaluations, commentary, quiz results and game reports are produced automatically using the Stockfish chess engine and an open opening dataset. They are for training purposes; they are not promised to be error-free, to lead to any particular result or to bring success in competition.

8. Availability

Reasonable care is taken to keep the Service running without interruption or error, but maintenance, faults or problems with third-party services may cause interruptions. The Service may be discontinued in whole or in part; where possible this will be announced in advance.

9. Suspension and closure

Accounts that break these terms seriously or repeatedly may be suspended or deleted. You may close your account at any time yourself from the account settings or profile page, or ask for it to be deleted by writing to [email protected] from the email address registered to your account. For an account made with a username, the owner’s parent or guardian may also ask for it to be deleted by writing to that address. When an account is suspended, the person’s coaching is suspended with it; when the account is restored the coaching does not come back by itself, and stays suspended until an admin approves it again. A closed account and its data cannot be restored.

10. Limitation of liability

The Service is provided “as is”. To the extent permitted by applicable law, no liability is accepted for indirect damage arising from the use of, or inability to use, the Service. This limitation does not affect liability for intent or gross negligence, or the mandatory rights you have under consumer law.

The Service may link to third-party websites (for example, the lichess and Chess.com game links in reports). Their owners are responsible for their content, rules and privacy practices.

12. Changes

These terms may be updated. The current version is published on this page with its effective date. Significant changes are announced on the site; continuing to use the Service after a change means you accept the updated terms.

13. Governing law and disputes

These terms are governed by the laws of the Republic of Turkey, and the courts and enforcement offices of the Republic of Turkey have jurisdiction. Users acting as consumers keep their right to apply to the consumer arbitration committees and consumer courts where they live, and any mandatory protection given by the law of their country of residence.

14. Contact

Questions about these terms: [email protected].