Terms of Service

By accessing or using ChessGrains ("the Service"), you agree to these Terms. If you do not agree, do not use the Service. The Service is provided by the ChessGrains operators ("we", "us").

ChessGrains offers chess training, spaced-repetition scheduling, game review tools, and community deck sharing. Features may change. We do not guarantee uninterrupted or error-free operation.

You are responsible for activity under your account. Authentication is provided by Supabase; we do not store your password directly. You must provide accurate information and keep your credentials secure.

The ChessGrains name, logo, user interface, and original application source code (excluding third-party and GPL-covered components such as the Stockfish WebAssembly binary) are proprietary. The spaced-repetition scheduler implementation in this codebase is an original work inspired by published SM-2-style algorithms and is part of that proprietary offering unless otherwise stated in our repository license file.

Third-party engines, libraries, and datasets remain under their respective licenses; see Licenses. The spaced-repetition scheduler uses the published SM-2 algorithm; attribution to SuperMemo World appears on that page per their published policy.

You retain rights to content you create. By publishing shared decks or comments, you grant us a licence to host, display, and distribute that content as needed to operate the Service.

You must not upload unlawful, hateful, harassing, sexually explicit, or otherwise offensive material, or content that infringes others' rights. We may remove content and suspend accounts that violate these rules or our community standards.

Where the Service connects to Lichess, you must comply with Lichess terms and API policies. Other games may be added only as PGN you import yourself.

ChessGrains offers a paid Pro subscription. Pricing and features are shown on our Pricing page. Payments are processed by Stripe; we never receive or store your card details.

Subscriptions renew automatically each month at the price displayed when you subscribed, until you cancel. You can cancel at any time from your account's "Manage subscription" link; access continues until the end of the current paid period and no refund is issued for the unused portion of that period unless required by law.

Prices are shown in USD. Where Stripe Tax is configured for your jurisdiction, applicable sales tax or VAT is calculated and displayed at checkout. By completing checkout you authorise Stripe to charge your payment method on a recurring basis. We may change pricing or features on reasonable notice; any change will only apply to renewals after that notice.

UK consumers: under the Consumer Contracts Regulations 2013, by subscribing and beginning to use Pro features immediately, you consent to the supply of digital content starting before the end of the 14-day cancellation period and acknowledge that your statutory right to cancel that period is lost. This does not affect any other statutory rights you may have.

The Service is provided "as is". Engine evaluations and training recommendations are informational, not professional advice. To the fullest extent permitted by law, we disclaim warranties and limit liability for indirect or consequential damages.

We may update these Terms. Continued use after changes constitutes acceptance. Material changes will be reflected in the "Last updated" date above.

Questions: use the contact address published in our public notices or the email identified in our Lichess API User-Agent configuration.