Terms of Service

What this is

Chester is a personal chess training tool: it pulls your own game history from a Lichess or Chess.com account you link, analyses it, and turns what it finds into puzzles, lessons, and a coaching report. It's built by two people (Thomas and Jamie) as an independent project, not affiliated with Lichess, Chess.com, Anthropic, Stripe, or any chess federation. Chester is still early -- things may still change or break more than you'd expect from a finished product.

Accounts

You need to be at least 13 years old to create an account. You're responsible for keeping your password secret and for anything that happens under your account. One account per person -- don't share logins. You can delete your account at any time from Settings; see the Privacy Policy for exactly what that does and doesn't remove.

Your game data

The whole point of the app is analysing games you've actually played, fetched from the Lichess or Chess.com username you link -- link an account you actually play on. Don't link someone else's account without their say-so.

Chester and the AI features

Chester's coaching report, the AI training plan, and Ask Chester are generated by an AI model (Anthropic's Claude) working from your game data and whatever you type in. Treat Chester's commentary the way you'd treat a strong-but-fallible study partner, not verified chess truth -- it can misjudge a position or get a fact wrong. Don't paste anything into Ask Chester you wouldn't want processed by a third-party AI provider.

Membership & payments

Some features are gated behind a paid plan, billed monthly through Stripe. We never see or store your card details -- Stripe handles payment, and (as merchant of record) is responsible for collecting and remitting any sales tax or VAT due on your purchase.

Cancelling (downgrading to Free) stops future billing but doesn't refund the period you've already paid for -- you keep your paid plan's features until that period ends, and you can undo the cancellation any time before then from the Your Plan page. If you're in the EU or UK, you normally have a statutory 14-day right to withdraw from an online purchase without giving a reason; because subscribing gives you immediate access to paid features rather than making you wait out those 14 days, doing so here counts as asking for that immediate access and agreeing your withdrawal right ends once it begins -- same as it would for any other service that starts working for you right away. If that doesn't sit right with you, cancel before you're next charged, or just get in touch (see Questions) if something's gone wrong with a charge.

Acceptable use

Don't try to break the app, scrape it at scale, abuse the bot/engine endpoints outside normal play, or use it to harass anyone. Puzzle stats, streaks, achievements, and bot stars are meant to reflect your own actual play -- don't script or automate your way to them.

No warranty, limited liability

The app is provided as-is. Engine evaluations, puzzle solutions, and AI commentary are generated automatically and can be wrong. We're not liable for decisions made based on anything the app tells you (chess or otherwise). To the extent the law allows it, our liability to you for anything else is capped at whatever you've actually paid us in the 12 months before whatever happened -- which, for anyone on the Free plan, is nothing.

Governing law

These terms are governed by Irish law, and any dispute that actually ends up in court goes to the Irish courts -- though we'd much rather just hear from you first (see Questions).

Changes

These terms might change as the app does. Significant changes will be reflected here with an updated date.

Questions

Email thomas.coase@gmail.com or jpk031004@gmail.com -- or reach out to whichever of us you already know.

Privacy Policy

What we collect

When you create an account: your email address, name, a password (stored as a bcrypt hash -- we never see or store the actual password), a username you choose, and the Lichess or Chess.com username you link. As you use the app: puzzle attempts and progress, session/streak/XP data, bot results, any training goals you type in, and questions you ask Chester. A session cookie keeps you signed in -- functional, not a tracking cookie. A handful of display preferences (dark mode, board colour, piece style) are saved directly in your own browser's storage and never sent to us at all.

What we fetch on your behalf

Using the Lichess or Chess.com username you link, the app fetches your public game history from that platform's own public API -- the same games anyone could already look up on that platform. That data (plus the engine's analysis of it) is what everything else in the app is built from. Because a game record inherently includes both players, this also brings along your opponents' public username and moves from that same game -- never anything about them beyond what's already public on that platform.

What we don't do

No ad trackers, no analytics-for-advertising, no selling or renting your data to anyone. Nothing here exists to be monetized by tracking you.

Payment information

If you subscribe to a paid plan, your payment goes directly through Stripe -- we never see, receive, or store your card number or other payment details. We only ever hold what Stripe tells us back: which plan you're on, whether your subscription is active or about to lapse, and an opaque Stripe customer/subscription reference (not financial data) so we know which Stripe account is yours.

Who we share data with

• Anthropic (Claude) -- receives your game/pattern data and whatever you type into Ask Chester, in order to generate Chester's coaching text, the AI training plan, and Ask Chester's answers.
• Stripe -- handles payment for paid plans as merchant of record; receives your email and whatever billing details you give it directly. See Payment information above for what we ourselves hold.
• Resend -- sends password-reset and email-verification emails on our behalf; receives your email address and name for that purpose only.
• Lichess / Chess.com -- receives the username you've linked when the app fetches your public game history from their API (this is a request to their public, unauthenticated API -- no password or login credential for that platform is ever collected or sent).
• Hosting infrastructure (Railway) -- runs the app and database; doesn't get separate access to do anything with your data beyond that.

We don't share your data with anyone else. Anthropic, Stripe, and Resend are all based outside Ireland/the EU, so using Chester means your data is processed there too, under each provider's own safeguards for exactly this kind of international transfer.

Deleting your account

Settings → Delete account removes your user record, sessions, puzzle progress and session history, reset/verification tokens, and any coach reviews you've left, immediately and permanently -- and cancels any active paid subscription right away rather than leaving it running. One thing it doesn't remove: engine-analysed game data is cached by platform username (not by account) so it doesn't need re-analysing if you or someone else looks at the same public games again -- that cache isn't tied to your account anymore once it's deleted, but it isn't wiped out either, since the underlying games were already public.

Your rights

You can ask us for a copy of what we hold on you, or ask us to correct anything that's wrong. Deleting it yourself is instant from Settings, no need to ask. If you think we've mishandled your data, you can complain to Ireland's Data Protection Commission (dataprotection.ie) -- though we'd genuinely rather you told us first, so we can actually fix it.

Children

Not intended for anyone under 13.

Changes

If what we collect or share changes meaningfully, this page will be updated with a new date.

Questions

Email thomas.coase@gmail.com or jpk031004@gmail.com -- or reach out to whichever of us you already know.