Zugzwanged
Privacy policy
Last updated: July 3, 2026
Zugzwanged is a chess training app. This policy describes what data we store, why we store it, and what we do — and don't do — with it. The short version: we store what the product needs to work, and nothing else. No ads, no tracking, no selling of data.
What we collect
- Account data — your username, email address, and a hashed password (we never store the password itself). Your timezone is stored so streaks and daily stats match your local day.
- Linked chess accounts (optional) — if you choose to connect them, your Chess.com and/or Lichess usernames, used to import your publicly available games from those services.
- Imported games — the public game data (moves, opponents, dates, results) fetched from Chess.com and Lichess for the accounts you linked. This data is already public on those platforms.
- Training data — your puzzle attempts, ratings, opening repertoires, spaced-repetition schedules, and training history. This is the core of the product: it's how the app knows what to train.
What we don't do
- No advertising and no ad networks.
- No third-party analytics or tracking SDKs.
- No selling, renting, or sharing of your data with third parties for their own purposes.
- No collection of data beyond what's listed above.
Cookies
We use a single, strictly necessary HTTP-only session cookie to keep you logged in. There are no marketing or analytics cookies, so there's no cookie banner — there's nothing to consent to.
Third-party services
- Cloudflare — network proxy and email routing for our domain.
- Resend — sends transactional email only (password resets). Your email address is shared with Resend solely to deliver those messages.
- Chess.com and Lichess public APIs — used to fetch your public games when you link an account. We send them your linked username; their own privacy policies govern their services.
Where your data lives
Zugzwanged is operated from Denmark and data is stored on servers in the EU.
Your rights and deleting your data
You can change your email and password in Settings. You can delete your account from Settings at any time — this permanently removes your account and the data associated with it. For access or export requests, or anything else, write us and we'll sort it out.
Children
Zugzwanged is not directed at children under 13, and we don't knowingly collect data from them.
Changes
If this policy changes in a way that matters, we'll note it here with a new date at the top.