Privacy

Nothing about you or your games. Checkmate Central has no accounts, no database of people, and no way to send your games anywhere. The analysis runs on your own machine, in your browser, using a chess engine compiled to WebAssembly. A game you paste in never leaves the tab it was pasted into.

Two things are counted on the site's own server, both anonymous and both described in full below: how often parts of the site are used, and the rating checker's tally of levels, with no name in it.

So that a position is never analysed twice, and so a half-finished review survives a reload, some things are kept in your browser's own storage. They stay on the device and are readable only by this site:

• Evaluated positions, in an IndexedDB database called chess-insight. This is a cache; deleting it only costs engine time.
• Finished analyses and the last review you ran, in an IndexedDB database called chess-insight-analyses, so a review of forty games does not have to be paid for twice.
• The last username you searched on each site, in two localStorage keys, so the field is not empty next time.
• Your progress through the lessons: which practice puzzles you have solved and the days you practised, so a streak can be counted. One localStorage key, names no one, and is deleted by the same button.
• Your settings — theme, sound, and how deep the engine searches — in a few more small keys.

All of it goes when you clear this site's data in your browser, and the delete button in the settings menu clears everything except the settings. Nothing here is sent anywhere, and no part of it is used to identify you.

When you search for a username, your browser asks that site's public API for the player's public games — the same data anyone can read from their site. The request goes from your browser straight to chess.com or to lichess; it does not pass through anything of ours, and the response is not stored anywhere except your own browser.

Each site sees that request the way it sees any visit to its public API. What they do with it is governed by chess.com's privacy policy and lichess's, not this one. Checkmate Central is not affiliated with, endorsed by, or connected to either of them.

The “copy link” button on a game puts the whole game inside the link, in the part after the #. That part is special: browsers never send it to a server. It is not in the request for the page, not in any log, and not in the referrer passed to a site you click through to afterwards. Making a link and opening one both happen entirely on the machines doing it, which is the same promise as the rest of this page.

The other half of that is worth being plain about: whoever has the link has the game. That is what a link is for, but it means a game posted in public is public — the same as pasting the PGN itself would be. Nothing about it is stored here either way, so a link cannot be revoked; if you would rather it were not out there, do not post it.

Visits are counted, so it is possible to know whether anybody is using this and which pages are worth improving. It runs on Vercel Web Analytics, chosen because it does the job without cookies and without following anyone around. Vercel processes those requests on our behalf, under their privacy policy.

What it records is a page view: which page, roughly where in the world the request came from, whether it was a phone or a desktop, and which site linked to it. Nothing is stored on your device — no cookie, no identifier, nothing to consent to under the rules that govern storage, which is why there is no banner.

Being precise about the one part that is not nothing: to tell a returning visitor from a new one within a day, Vercel takes the ordinary details of the request — your IP address and your browser's user agent — and turns them into a hash using a secret that is thrown away and replaced every day. The IP address is not kept, the hash cannot be turned back into it, and by the next day the same visitor is a different hash. It is as little as counting can be done with, but it is not literally nothing, and a privacy page that said otherwise would be wrong.

None of it touches your chess. Your games, the analysis, your saved reviews and your solved puzzles never leave your browser, and never appear in any request. A page view says a page was opened; it says nothing about what you did there.

If you would rather not be counted at all, the settings menu has a “Do not count my visits” switch. It is kept in your browser's storage, like the other settings, and it stops page views from this browser being sent.

• No session recording, no heatmaps, and no profile of you across visits.
• No advertising, no ad networks, and no ad cookies.
• No cookies at all: the site sets none, and needs none — the visit counting works without them.
• No Google Analytics, no Meta pixel, no third-party trackers or beacons.
• No email address, because there is nothing to sign up for.

The site itself is a set of static files. Whoever serves them to you — a web host, a CDN, your own machine — can see the ordinary things any web server sees: the address of the request, your IP address, your browser's user agent. That is a property of the web rather than of this tool, and it is unrelated to your games, which never appear in any request.

Nothing here identifies anybody, children included. There is no account, no name, no email, and no profile — the visit counting cannot tell one person from another, so there is no age gate because there is nothing to gate.

If this ever changes — if accounts or server-side storage are added — this page will say so before the change ships, with a new date at the top. A policy that quietly grows a data-collection section is not worth reading.