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What Peekchess keeps, and why.
Starting does not need an account. Your progress is saved against an anonymous account tied to that browser, with no name and no email on it. If you never sign up, we never learn who you are.
We keep your email address, either the one you type or the one Google or Apple gives us when you sign in with them. It is used to sign you in and to reach you about your account. It is not sold, not shared, and not added to any marketing list.
We store the username you give us and read your public games from Chess.com or Lichess, only ones played this calendar year: up to 250 from each site when you connect, and more of this year's as time goes on. An engine checks those games for mistakes and we keep what it finds, because that is what decides which puzzles you are shown. Only games that are already public are read, and we never ask for your password on either site.
The puzzles you were served, whether you solved them, your rating, and your settings. If you choose a display name to appear on the leaderboard, that name is visible to other players. Nothing else about you is.
We use PostHog to count page views and button presses, and to record how the screen changes as you use the site, so we can watch back where people get stuck. Anything you type is masked in the recording. Recordings are filed under your account's id, and nothing else about you, so that if you report a problem we can look at what happened.
We also count visits ourselves, in our own database: which pages were opened, which buttons were pressed, where you arrived from, and roughly what device and country. To tell one visitor from another we keep a random id in a cookie on peekchess.com. It says nothing about who you are, and is linked to your account only once you have one.
We use the Meta pixel to see whether our ads on Facebook and Instagram bring people here. It tells Meta which pages were opened, and when someone signs up or starts a trial, and it sets a Meta cookie in your browser. It is not told your email, your games or your rating.
The database and sign in are run by Supabase, the site is hosted by Cloudflare, and Google or Apple sees your email only if you sign in with them. If you subscribe, payment is handled by Stripe, and we never see your card. Errors the site runs into are reported to Sentry with your account's id and nothing else. For Peek AI to explain positions from your own games, the position and your rating are sent to OpenRouter and OpenAI. Your name and email are not. Nobody else receives your data, and none of it is sold.
You can delete your account yourself. On the website it is Delete my account at the bottom of your account page; in the phone app it is You, then Account, then Delete my account. How to delete your account has the steps.
It happens at once and cannot be undone: your login, rating, history, games and everything else stored against the account are removed. Error reports and screen recordings at Sentry and PostHog carry only the account's id, which leads nowhere afterwards, and go when those services' retention runs out. Stripe keeps its own record of past payments, as the law requires.
If you cannot sign in, email daniel.kozusek@gmail.com and we will delete it for you. You can also ask for a copy of what is held.
Questions go to daniel.kozusek@gmail.com. Last updated 26 September 2026. Terms.