Sudoku Solver
Paste a puzzle from paper, a newspaper, or another app and Pure Sudoku will finish the grid instantly. Type the digits you already know, then tap Solve to see a logically sound solution you can double-check or print.
Enter your puzzle
Tap any square, type digits 1-9 (or use the keypad), then press Solve to fill the remaining cells.
Trusted Pure Sudoku logic
The solver uses the same engine that powers our playable boards, so every answer is unique and double-checked for validity before it is shown.
- Highlights conflicts instantly so you can fix typos before solving.
- Marks the digits you entered in a lighter tone and colors solved cells in Pure Sudoku blue.
- Works great on phones—tap a cell, then tap a keypad number to fill it.
Want to improve your solving skills?
Try our tutorials after you see the answer.
Explore solving strategies →When to use a Sudoku solver
Solvers are perfect when you want to check your work, rescue a nearly-finished newspaper puzzle, or verify that a friend’s custom board is solvable before spending time on it. If you love the challenge, try solving manually first and keep this tool as a safety net.
- Scan a paper board row by row and fill in the matching squares above.
- Use the Clear board button to reset between puzzles or after printing a solution.
- On iPhone, tap a cell and use the keypad so you never need to open the keyboard.
- Need hints instead of a full solve? Jump into the how to play guide for step-by-step help.
How the Pure Sudoku solver works
We run a constraint-driven backtracking algorithm that mirrors human logic before brute force. The solver checks rows, columns, and boxes for conflicts, validates that the clues you entered produce exactly one solution, and then fills the empty cells.
- Every puzzle is solved locally in your browser—nothing is uploaded.
- Conflicts are highlighted in red so you can correct mistakes fast.
- If a puzzle has no solution, you will see a friendly error instead of a blank page.
Next steps after solving a puzzle
Use the solution as a teaching tool, then dive back into live play, printable grids, or multiplayer races to test what you learned.