NineFold

Sudoku that works entirely on your device. No account, no server, no cloud sync — generation, solving, grading, saved progress, statistics and your Pro unlock all resolve offline.

Coming soon to the App Store and Google Play.

• Five difficulties, graded by the techniques a solve requires rather than by clue count
• A daily challenge that is the same puzzle on every device, derived from the date with no server
• A daily archive going back to the start, every date replayable
• Hints that fill in the next digit on one tap — and when the next step only rules candidates out, they name the technique and show you the pattern instead
• Pencil marks, undo and redo, and a game that saves itself as you play
• Streaks, best times and per-difficulty records, kept on the phone and nowhere else
• Colourblind-safe palettes, full screen-reader support, and large-text support — all free, always

Free, with one optional unlock

NineFold is free and ad-supported, with five hints a day and the option to earn up to five more by watching a short video. NineFold Pro is a single one-time purchase — not a subscription, so it cannot lapse — that removes every ad and lifts the daily hint allowance. Nothing in the app ever stops you starting, continuing or finishing a puzzle: run out of hints and every puzzle is still completable, you are simply not told the next move. There are no lives and no refill timer.

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hello@ninefoldhq.com