sudokUI › Privacy
What sudokUI sends, and what it keeps
sudokUI runs on your device. It has no account, no cookie banner and no advertising, and by default it sends nothing about you. This page lists everything that leaves the device, exactly.
By default: two lines per game, while online
When a game starts and when it is solved, the app sends one short line to sudokui.app: which of the two it was, the puzzle’s difficulty band, the solve time rounded down to a 15-second step (two hours and up count as one step), whether the app runs installed or in a browser tab, and the app’s version. The server adds the country the connection came from, as Cloudflare reports it, and keeps the counts for three months in Cloudflare’s Workers Analytics Engine.
That is all. The line carries no name, no account, no cookie, no device ID and no IP address: the server reads the address only to refuse floods, in memory, and never writes it down. One game cannot be linked to another. Nothing is stored on your device for this. Offline, nothing is sent and nothing is kept.
A practice puzzle, which starts part-way through, sends nothing. Restarting a puzzle does not count as a new game.
If you ask: counting your offline plays too
Settings has a switch, “Help count plays, including offline ones”. It is off until you turn it on. On, the app keeps the same lines on your device while you are offline and sends them, marked as sent late, the next time it is open online. It also remembers the day you turned the switch on, so a line can say whether this device had played on an earlier day. Both are deleted the moment you turn the switch off.
Still no identifier: the lines are the ones above, plus “sent late”, “counting on” and “played before”. They let the counts estimate how much is played offline without following anyone.
The daily puzzle’s times
After an unassisted solve of the daily, the win screen offers “Send my time and compare”. Only if you tap it, the app sends your time, the finished grid and a random token it keeps for that day, so the same time is not counted twice. The server keeps the time in 15-second steps with the day’s other times, and the token with it. Nothing links one day’s token to another day’s.
Share links
A link you share carries the puzzle, its band and rating, up to three technique names and, if you choose to challenge someone, your time in seconds. When someone opens it from outside sudokui.app, the server counts one landing, with the band and the country; who opened it is not recorded.
What is never collected
No account, no e-mail address, no password, no cookie, no fingerprint, no advertising, no third-party script. Your games, pencil marks, statistics, technique record and daily streak stay in your browser’s storage, on your device, and leave it only in the ways this page describes.
Who runs this, and how to check
sudokUI is run from Norway by its author and served by Cloudflare. The source code, including everything this page describes, is public: github.com/AImenes/sudokUI. Questions and corrections are welcome as an issue there.