Claire's Sudoku

About Claire's Sudoku

Claire's Sudoku is two things in one app. The first is a sudoku school. A short placement test of five boards finds where you are, and Claire Kaplan then teaches thirteen techniques one at a time, from the full house and the naked and hidden single through pairs, triples, the X-Wing, the Y-Wing, the XYZ-Wing and the Swordfish. The lessons are grouped into six belts, each played on teaching boards checked so the hardest move needed is the one being taught, and a certificate marks each belt.

The second is a complete sudoku game. Puzzles are generated on the phone at five difficulties, Easy to Master, and there is one daily puzzle, the same for everyone, on the newspaper ramp: easy on Monday, rising through the week to a Master puzzle on Saturday. You get pencil notes, unlimited undo and one hint per puzzle, which fills in a single correct digit. A timer and a mistake tally are there but off until you switch them on.

A one-minute Daily Drill asks five quick questions on the techniques you have learned, bringing back the ones you stumbled on. The streak counts any day you did something, whether a puzzle, a lesson or a drill. The board can be light, dark or Night, a warm red screen for playing in bed.

The app is made by Built by Foundry and came out on the App Store in July 2026. It has no ads, no account and no sign-in, works offline, and every lesson, difficulty and daily puzzle is open. It suits players who want to get better at sudoku, not only to play it.

How to play Claire's Sudoku

1. Open the daily puzzle from the home screen.
2. Fill each empty square with a digit from 1 to 9 so that every row, column and 3x3 box holds each digit once.
3. Use notes to pencil in candidates, and undo freely.
4. Use your one hint if needed: it fills in a single correct digit.
5. Come back each day; the daily gets harder from Monday to Saturday.

Screenshots

Tips

• Scan each box for hidden singles first: a digit that can go in only one square of a box.
• Take notes on harder days; later in the week the daily needs more than singles.
• When stuck, look for a naked pair: two squares in a unit with the same two candidates clear those digits from the rest of the unit.
• Do the lessons in order; each one prepares the next, and later dailies use them.

Questions