Terms of Use

Last updated: October 23, 2026

SudokuSudoku is a free Sudoku game in the browser. These terms cover playing, the optional account, the contact form, and ads. What happens to information is in the privacy policy.

Playing

You can play without signing in and without paying. A puzzle is generated in your browser when you start. The daily is the same Not Easy grid for a UTC date, seeded from that date. Without an account, progress, settings, your stats, and the skill ladder stay in local storage on the device.

Optional account

An account is optional. The game still plays if you never sign in. It lets a streak, stats, settings, skill progress, and an unfinished puzzle come back after the browser clears storage, or on another device.

Sign-in is your email and a link or a 6-digit code. There is no password, and no name is stored. The code and the link expire after 15 minutes and each works once. The server stores a hash of them, not the link or the code.

If you sign in, the server keeps your email and a copy of the game data: stats, daily completions, streaks, settings, skill progress, and the puzzle in progress. The session is a cookie page scripts cannot read. It is sent only over HTTPS, not to other sites, and it lasts about 180 days. Sign-in uses Cloudflare Turnstile, the same spam check as the contact form.

Delete my account, in Stats or Settings, deletes the email and the saved game data on the server. The copy on the device stays until you clear site data. I do not sell email addresses or game data.

Children

The puzzles are fine for children. The account asks for an email, so it is not for anyone under 13. I do not knowingly collect personal information from anyone under 13. If a child signed in, delete the account in Stats or Settings, or ask me through the contact form.

The contact form

The contact form is for a bug, a technique page that looks wrong, or a result that does not match the rules. Don't send spam, threats, anything illegal, or someone else's personal information. Don't try to break the site, overload it, or take access you were not given. I can ignore a message, and I can delete an account used to abuse the site.

Ads and other sites

The game is free. Google may measure visits and show ads, as the privacy policy describes. I don't pick the ads, and an ad is not an endorsement. The links page points at other people's sites. Their rules are theirs.

What you can copy

The writing, the code, the design, and the name SudokuSudoku are mine. Sudoku itself is not. You can play, share a result the game offers, and link here. You don't get a license to copy the explanations or the code and publish them as your own.

No warranty

The site is free and provided as it is. I don't promise it will always be available, that a grade will match another site's label, or that it will have no bugs. I can change a feature, including the account, or take the site down. To the extent the law allows, I am not liable for loss from using it.

Changes

If these terms change, the date at the top changes too. Using the site after that means you accept the update. If you don't, stop, and delete the account if you made one.

Questions

The contact form comes to me.