Sudoku solver
Only here Reads your board from a screenshot in your browser, solves 6×6 Mini Sudoku as well as 9×9, walks every hint to the next digit through named techniques, and grades the board by the hardest one it needs.
For classic 9×9 Sudoku, 6×6 Mini Sudoku (as on LinkedIn) and 4×4 boards. Type in your board, then play with hints that walk you to the next digit the way a person would find it.
Select a square and type its digit (arrow keys move, Backspace clears), or use the number pad below. Or load a screenshot: it is read in your browser and never uploaded. Then switch to Play.
How the hints work
Each hint is the next digit a person can find, plus any steps needed to get there, using these techniques in order from easiest to hardest:
- Naked single: a square where only one digit is left.
- Hidden single: a row, column or box where a digit fits in only one square.
- Pointing and box/line reduction: a digit locked to one line inside a box (or one box inside a line) is ruled out elsewhere.
- Naked and hidden pairs, triples and quads: a group of squares that holds a group of digits between them.
- X-wing, Swordfish and XY-wing: patterns across several rows and columns.
How the grade works
"Check and grade" solves the board with those techniques and grades it by the hardest one it needs: Easy (singles only), Medium (pointing, box/line, naked pairs), Hard (hidden pairs, triples), Expert (X-wing, XY-wing, Swordfish, quads) or Beyond logic when they get stuck and the board needs a guess. It also says whether the board has exactly one solution, found with an exhaustive search, so the answer is certain.
Reading screenshots
The image never leaves your device. The solver finds the board by its heavy outer border, then compares the ink in each square with digits your own browser draws in common fonts, and picks the closest. Squares it isn't sure about get a dashed outline; check every digit against your screenshot and retype any that are wrong.
"Show candidates" lists the digits still possible in each empty square, after every elimination those techniques allow.
You enter the boards yourself; Grind Toolkit doesn't copy anyone's puzzles. Not affiliated with LinkedIn or any puzzle publisher.