Sudoku Atlas — get help, ask a question, or report a bug.
Email sudokuatlas@proton.me for any question, bug report, or feature request. We typically reply within a few days.
When reporting a bug, please include your device model, iOS or Android version, and the steps to reproduce the issue.
The free version includes a new Daily Puzzle every day (see below) and a demo bank of puzzles across all grid sizes at every difficulty level — enough to try everything the app offers. The one-time unlock adds unlimited puzzle generation, seed-based puzzles, and unrestricted access to all grid sizes from 4×4 to 25×25.
At UTC midnight. The puzzle difficulty cycles through easy, medium, hard, and maximum, so each day brings a different challenge.
Sign in with the same Apple ID or Google account you used to buy the unlock. The App Store and Google Play handle restore automatically — you should not be charged again. If it doesn’t restore on its own, look for a “Restore Purchases” option in the app settings.
Focus Mode dims cells that don’t share the row, column, or box of your selected cell. It reduces visual noise and makes it easier to spot patterns, especially on larger grids.
Stamp Mode lets you lock a digit and then tap cells to apply it as a glyph stamp — useful for filling in confident answers quickly. You can also use pencil marks to track candidates. Both modes are available at the same time and you can switch between them freely.
You can save a snapshot of the board at any point during a solve. If you go down a dead end, restore the checkpoint to pick up from where you saved. You can save multiple checkpoints and choose which to restore.
Every puzzle has a short seed code. Share it with someone and they get the exact same grid in the exact same starting state — guaranteed, because generation is deterministic. Use it to race a friend or compare solving strategies on identical puzzles.
No. See our Privacy Policy for the full commitment in writing. There is no ad SDK, no analytics framework, and no account system in this app. That is not going to change.
Everything — puzzle progress, settings, statistics — is stored locally on your device and never leaves it. See the Privacy Policy.
Email sudokuatlas@proton.me. Include your device and OS version, and for bugs, the steps to reproduce. Feature requests are very welcome.
Read the full Privacy Policy. The short version: no data is collected, no network requests are made, everything stays on your device.