Terms of Service

NabuChess is operated by NabuChess Ltd, a company registered in England and Wales under number 14829301, with its registered office at 27 Bridgewater Street, Manchester M1 5AR, United Kingdom.

“We”, “us” and “our” mean NabuChess Ltd. “You” means the person or organisation using the service. By creating an account you accept these terms.

You need an account to use anything beyond the public marketing pages. You must give accurate information and keep your credentials secure — you are responsible for activity under your account.

You must be at least 16 years old to hold an account. NabuChess is not intended for children under 16 and we do not knowingly create accounts for them. There is no guardian-managed account type: every account belongs to the person using it.

If we learn that an account belongs to someone under 16 we will close it and delete the personal data associated with it, as described in the Privacy Policy.

Any user can become a coach by completing coach verification. Students can only be assigned to a verified coach, and no coaching relationship starts without both sides accepting it.

A student may work with up to 3 coaches at once and may end any of those relationships at any time without ending the others. A student controls what each coach can see about work set by other coaches.

We are not a party to the coaching arrangement. Fees, scheduling, safeguarding obligations and the quality of instruction sit between the coach and the student.

• Coaches must hold any qualification, insurance or background check their jurisdiction requires.
• Coaches must not use student data for anything other than coaching that student.
• We may suspend a coaching relationship immediately where we receive a credible safeguarding report.

Use the service for chess coaching, training and play. Do not use it to harass anyone, to distribute unlawful material, to scrape the service at scale, to circumvent rate limits, or to resell access without a written agreement with us.

Engine assistance during rated play on connected platforms is cheating on those platforms and a breach of these terms here. Analysis after a game is exactly what the product is for; assistance during one is not.

You keep ownership of every plan, annotation, comment, video, PGN and note you upload. You grant us a licence to store, process and display that content strictly to operate the service for you and the people you share it with.

Video and audio you upload for review is private to the thread it is posted in. We do not use customer content to train machine learning models.

Puzzle and game data comes from the Lichess open database, released under Creative Commons CC0. Puzzle data is public domain — no attribution required. Their engine and UI code is copyleft and is not used here. We redistribute that data inside the product on that basis. NabuChess is not affiliated with, endorsed by, or supported by Lichess.

No Lichess code runs in your browser. The board is react-chessboard under the MIT licence over an annotation layer we wrote; move generation, FEN, SAN and PGN handling are chess.js under BSD-2-Clause. Both licences are permissive and neither imposes obligations on you.

Stockfish is licensed under the GNU General Public License v3 and runs only on our servers, as a separate service. No engine code is sent to your browser, and there is no facility to upload or run an engine binary of your own — a user-supplied executable is a security boundary we are not willing to cross. Source for the Stockfish build we run is available on request, as GPLv3 requires.

Student accounts are free. The Coach plan is billed monthly or yearly in advance, in pounds sterling, through our payment processor. Prices exclude VAT, which is added where applicable. The Coach trial runs 14 days and needs no payment details; if you do not subscribe at the end of it, the account reverts to the free tier and nothing is charged.

Yearly plans can be refunded pro rata within 30 days of purchase. Monthly plans are not refunded for partial months, but cancelling stops the next charge immediately.

You can cancel at any time from billing settings, in one action. Your plan stays active until the end of the paid period, then drops to the free tier — nothing is deleted at that point.

We may suspend or close an account that breaches these terms, after notice where it is safe and lawful to give it. For serious safeguarding or security matters we act first and explain afterwards.

On closure you have 30 days to export. After that we delete personal data on the schedule set out in the Privacy Policy.

We aim for 99.9% monthly availability. Planned maintenance is announced in the product and by email at least 48 hours ahead, and scheduled outside European evening hours where possible.

Support response targets are part of your plan. They are targets, not contractual guarantees, unless a separate agreement says otherwise.

Nothing in these terms limits liability for death or personal injury caused by negligence, for fraud, or for anything else that cannot lawfully be limited.

Subject to that, our total liability in any 12 month period is limited to the fees you paid us in that period. We are not liable for lost profits, lost opportunities or the consequences of decisions taken on the basis of engine evaluations or progress statistics.

We may change these terms. Material changes are announced in the product and by email at least 30 days before they take effect, and the version number above changes with them.

If you do not accept a change, cancel before it takes effect and we will refund any unused portion of a yearly plan.

These terms are governed by the law of England and Wales, and the courts of England and Wales have exclusive jurisdiction.

Talk to us first. Most disputes are resolved by email within a week; formal proceedings should be a last resort for both of us.

Write to legal@nabuchess.com, or by post to NabuChess Ltd, 27 Bridgewater Street, Manchester M1 5AR, United Kingdom. We answer legal correspondence within five working days.