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Privacy Policy

Last updated: October 15, 2026

Introduction

Sudoku69 is a free browser-based Sudoku game. No account creation or login is required to play. Signing in with Google is optional. This policy explains what data we collect and how we use it.

Data We Collect

We do not collect personal information unless you choose to sign in. We do not ask for payment information, and there are no registration forms on this site. Playing anonymously stores nothing about you on our servers.

Accounts (optional Google sign-in)

You can sign in with your Google account. Sign-in is handled by Supabase Auth together with Google Identity. When you sign in we receive from Google:

  • your Google account ID
  • your email address
  • your display name
  • your profile picture URL

This information is stored by Supabase in the authentication database of our project. We use it only to show that you are signed in and, in the future, to keep your progress across devices. We never see or store your Google password.

Your session token is kept in your browser's localStorage under the key sudoku-auth. Signing out removes it.

To delete your account and the data above, email privacy@sudoku69.com from the address you signed in with. We delete the account manually within 30 days. Self-service deletion will be added later.

Google Analytics

We use Google Analytics 4 (GA4) to count visitors and see which pages are used. We never sell your data. Google processes this data on our behalf, under their own privacy policy. Our tracking ID is G-8JDMVHP06N.

If you are in the EU/EEA, the UK, Switzerland, Turkey, or Quebec, you see a small consent banner. Google Analytics loads only after you click "Accept". Until then nothing is loaded, and the banner stays on screen (it does not disappear on its own). "Read more" brings you to this page.

Everywhere else, Google Analytics loads without a banner. You can still block it with your browser's privacy settings or the Google Analytics Opt-out Browser Add-on.

Besides page views, Google Analytics receives gameplay events:

  • a puzzle started, solved or abandoned, with the game mode, difficulty, puzzle ID, time taken, number of moves, wrong digits, undos, whether notes were used, and progress in per cent
  • resuming a saved game, switching game mode, changing colour theme, signing in or out, and puzzle loading errors
  • page-speed measurements (Core Web Vitals)
  • which theme you use, whether you are signed in, and which mode you last played

If you are signed in, we send Google Analytics your account's internal random ID (a UUID from our sign-in system), so visits from your different devices can be linked. We never send your name, email address or photo to Google Analytics. If you are not signed in, no ID is sent.

All of this is sent only when Google Analytics is allowed to load, under the consent rules above. Nothing here is used for advertising.

Google Analytics uses two cookies: _ga and _ga_<id>.

Cookies and your choice

To decide whether you see the consent banner, the site asks our own server for your country. Our host, Vercel, derives this from your IP address. Only the country or region code is sent back to your browser, and it is never stored by us. A successful result is kept for your browser session in sessionStorage. If it says no consent is required where you are, it is also remembered for 7 days in localStorage (inside sudoku-consent), then checked again. A failed lookup is not stored.

Your choice is remembered in your browser's localStorage, under the key sudoku-consent. An accepted choice is remembered for about 13 months. A turned-off choice is remembered for about 6 months, then we ask again.

You can turn Google Analytics on or off at any time with the switch below (the "Cookie settings" link in the footer leads here). Turning it off stops Google Analytics and removes its _ga cookies. The switch works for every visitor, also outside the regions above.

Vercel Web Analytics

We also use Vercel Web Analytics for aggregated visit statistics. It sets no cookies and stores nothing in your browser. Visitors are counted by a hash made from the incoming request, and that hash is discarded after 24 hours. It contains no personal identifiers, so the data cannot identify you or follow you across other websites. For each page view it records:

  • the time and the page URL
  • the referrer and filtered query parameters (for example ?ref=)
  • your country, region and city, taken from the request
  • your device type, operating system and browser version

Query parameters on our sign-in return page are removed before anything is sent. Because it uses no cookies and no personal identifiers, Vercel Web Analytics runs for all visitors, without the consent banner. The banner and your consent choice cover Google Analytics only.

Local Storage

Your browser stores game data locally using localStorage. This data stays on your device and is never sent to our servers:

  • sudoku-settings — your theme preference (light, dark, or sepia)
  • sudoku-board-store — your current game state and progress
  • sudoku-auth — your sign-in session, only if you signed in
  • sudoku-consent — your Google Analytics consent choice if you saw the consent banner, or your country check result for 7 days if you did not need one

We cannot access, read, or modify this data. It exists only in your browser.

Third-Party Services

We use four third-party services: Google Analytics (usage statistics), Supabase (puzzle database and authentication), Google Identity (optional sign-in), and Vercel (hosting, country lookup for the consent banner, and Vercel Web Analytics). We do not use advertising networks, tracking pixels, social media widgets, or any other third-party tools.

Your Rights

You have full control over the data stored on your device and, if you signed in, over your account:

  • Clear localStorage through your browser settings to delete all local game data
  • Sign out to remove your session from the browser
  • Email us to delete your account and the profile data received from Google
  • Use the switch in "Cookies and your choice" to turn Google Analytics on or off (the "Cookie settings" link in the footer leads there)
  • Use browser extensions like Google Analytics Opt-out Add-on to disable analytics tracking
  • Use your browser's privacy or incognito mode to prevent any data storage

Contact

Questions about this privacy policy? Email us at privacy@sudoku69.com.