Learn why the next
Sudoku move works.

doku.su coaches from your current grid, one logical step at a time.

✓ Play without an account ✓ Hints that explain the logic

“What can this row prove?”

Try the coach

Find the next move without guessing.

Start with where to look. Reveal the useful evidence, name the pattern, and see why the move is safe only when you need the complete proof.

Try this on a real puzzle → This explanation comes from the same deterministic solver used in every coached puzzle.

Use logic firstEvery hint starts with a valid deduction.

Learn by solvingShort lessons lead to guided practice.

Set your own pacePractice without pressure.

Checkable by design

Every coaching message is bounded by facts rebuilt from the current grid.

Verified puzzle logicPuzzles have one solution, and every recommended move comes from the deterministic engine.
Start without an accountPlay and learn locally first. Create an account only when you want cross-device sync.
Learning survives a lost connectionAvailable lessons and local puzzles remain usable offline after they have been loaded.

Learn Sudoku one clear step at a time

doku.su rebuilds every clue from your current grid. It shows what to inspect, lets you reason, and reveals more only when you ask.

Learn why every digit from 1 to 9 appears once in each row, column, and 3×3 box.

Follow a clear path from scanning and candidate notes to singles and advanced patterns.

Start with where to look, then ask for the cell, the reason, or the digit only if you still need it.