Sudoku Solver
A sudoku solver that teaches while it solves: type or paste your puzzle (an 81-character string with dots for blanks works too) and step through the solution one logical deduction at a time. Each step names the technique — naked single, hidden single, locked candidates, naked or hidden pair and triple, X-wing, swordfish, XY-wing — explains in plain language why it works, and highlights the rows, columns and boxes involved while the pencil-mark candidates update live. Auto-play the whole solution with a running technique log, or solve instantly. Brute-force trial and error is used only when the logical ladder stalls, and every such step is clearly labeled. At the end you get a difficulty verdict based on the hardest technique that was needed, plus a printable solution sheet with the full technique log and PNG/SVG export of the solved grid.
Runs 100% in your browser — your puzzles never leave your device.
Read the full guide to this tool
Notes
- Implemented techniques, tried in order: naked single, hidden single (box, row, column), locked candidates (pointing and claiming), naked pair/triple, hidden pair/triple, X-wing, swordfish, XY-wing — and backtracking ("trial and error") only as the labeled last resort.
- Contradictory puzzles are rejected with a clear message, and puzzles with several solutions are flagged with a warning while one valid solution is still shown.
- The difficulty verdict reflects the hardest technique the solver actually needed, the same way human raters grade sudoku.
- Runs 100% in your browser — your words and puzzles never leave your device.
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