Privacy Policy
Last updated July 18, 2026
Square One (playsquareone.com) is a chess coaching app. This page says, in plain language, what data we handle and why. The short version: we store what the product needs to coach you, we sell nothing, and you can leave with your data deleted.
What we collect, and why
Account. If you sign up, we store your email address, a username, and your authentication credentials, managed by Supabase, our auth and database provider. Guests can play without an account; guest progress lives only in your browser's local storage.
Chess data. The product's whole point is studying your games. We store the games you play here, games you choose to import from Chess.com or Lichess (fetched from their public APIs at your request), your puzzle attempts, training progress, and the coaching signals derived from them, such as recurring mistake patterns and rating history. This data exists to coach you and is shown to you.
Payments. Premium subscriptions are processed by Stripe. Your card details go to Stripe, never to us; we store only your subscription status and plan.
Usage analytics. We use privacy-respecting product analytics (Vercel Web Analytics, and PostHog when enabled) to understand which features get used: events like "started a game" or "opened pricing." We do not run third-party advertising trackers, and we do not sell or share your data with advertisers.
Coaching explanations. To generate move explanations, the position and move context from your game are sent to large-language-model providers (such as OpenAI or Google) through our servers. These are chess positions, not personal conversations; we do not send your email or identity with them.
What we never do
We do not sell personal data. We do not show ads. We do not share your data with third parties except the processors named above (Supabase, Stripe, Vercel, analytics, and LLM providers), each used only to run the product.
Where your data lives
Account and game data live in Supabase (Postgres). The puzzle catalog is public, non-personal data served from an edge database. Local preferences, guest progress, and training streaks live in your browser's local storage and stay on your device.
Deleting your data
You can delete your account and its data from Settings inside the app, or by emailing us at the address below, and we will delete it. Clearing your browser storage removes all guest data.
Children
Square One is a general-audience chess app. We do not knowingly collect personal information from children under 13; a parent who believes a child has created an account can email us and we will remove it.
Contact
Questions or requests: lukenpowers3@gmail.com. If this policy changes materially, the date above changes with it.