Backtracking Algorithm

Sudoku
Solver

Play a live puzzle and sharpen your logic, or let the backtracking algorithm crack any custom Sudoku in milliseconds. Two modes — one engine.

Play Sudoku → Auto Solver

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Backtracking Search

The solver tries candidates cell-by-cell and backtracks instantly on constraint violation — guaranteeing a solution if one exists.

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Constraint Propagation

Row, column, and 3×3 box constraints are enforced simultaneously at every step — drastically pruning the search space.

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Brain Training Mode

Challenge yourself with the interactive puzzle — tap any cell and choose a digit. Logic, not guessing, gets you to the finish.

Interactive Play

Play a Sudoku Puzzle

Sharpen your mind with a classic 9×9 Sudoku. A pre-filled puzzle loads with empty cells ready for you to fill — click any cell to open the number pad and input your answer.

1Click "Play Sudoku" to open the puzzle grid.
2Click any empty cell to reveal the number pad (1–9).
3Select the number you believe belongs in that cell.
4Complete the full grid using pure logic — no guessing.

Play Sudoku →

AI Auto Solver

Let the Algorithm Solve It

Input any partial or complete Sudoku puzzle into the grid and hit Solve. The backtracking engine processes thousands of candidates in milliseconds and displays the completed solution instantly.

1Click "Auto Solver" to open the empty 9×9 grid.
2Enter your puzzle values cell by cell using the number pad.
3Click "Solve" and watch the grid complete itself.
4Reset and try another puzzle — the engine never fails.

Auto Solver →