Privacy Policy
Last updated: July 14, 2026
Endgame ("we", "our") is a chess endgame puzzle trainer available on the web and as a mobile app. This page explains what data we collect, why, and the choices you have. We built Endgame to work fully offline without an account — creating one is always optional.
Who we are
Endgame is operated by Teknolojig. Our backend runs on our own self-hosted Supabase instance — we are not routing your data through a third-party SaaS analytics platform. Contact us any time at privacy@chessendgametrainer.com.
What we collect
If you never create an account, your puzzle history, rating, streak and favorites stay only on your device (local storage on web, on-device SQLite in the app) — we never see them. If you sign in with email, we additionally store: your email address, a generated display username, your trainer rating, streak, solved/failed puzzle history, favorites, and daily-challenge results, so they sync across your devices.
How we use it
Solely to run the product: picking your next puzzle at the right difficulty, keeping your rating and streak in sync across devices, running the daily challenge and its leaderboard, and diagnosing bugs. We do not sell your data, and we do not use it to build advertising profiles outside of the ad consent described below.
Puzzle content
Puzzles come from the Lichess puzzle database, released under CC0 (public domain) — no personal data is exchanged with Lichess, and playing a puzzle never sends anything to them.
Advertising
The app shows ads served by Google AdMob: short interstitial ads at natural breaks between puzzles, and optional rewarded ads you choose to watch for an extra hint. We never show ads on the puzzle board itself while you're solving. Where required (EEA/UK), we ask for your consent to personalized ads via Google's User Messaging Platform before any ad loads; on iOS we also ask for App Tracking Transparency permission before requesting a personalized ad. You can decline both and still use the app and see (non-personalized) ads.
Cookies and local storage
The web app uses your browser's local storage to keep your progress when you're not signed in, and a session cookie when you are (via Supabase). We don't use third-party tracking cookies.
Data retention and deletion
We keep your account data for as long as your account exists. Email privacy@chessendgametrainer.com to request a copy of your data or full deletion — we'll act on it within 30 days.
Children's privacy
Endgame is not directed at children under 13, and we don't knowingly collect personal information from them. If you believe a child has created an account, contact us and we'll remove it.
Your rights
Depending on where you live, you may have the right to access, correct, export, or delete your data, and to object to or restrict certain processing. Email privacy@chessendgametrainer.com for any of these — no account required to ask.
Changes to this policy
If we make a material change, we'll update the date at the top of this page. Continued use of Endgame after a change means you accept the update.
Contact
Questions about this policy? Write to privacy@chessendgametrainer.com.