Sudoku - Free Online | FunToolX
Use Sudoku online for free, no download required. FunToolX offers hundreds of fun online tools.
About this tool
Sudoku is a free online game. Classic Sudoku with three difficulties and unique solutions. Play instantly — no install, no waiting. It runs entirely in your browser — no download or sign-up needed.
The 9×9 chessboard is divided into 9 3×3 squares. Some squares have been filled in with numbers (clues given by the title), and the numbers 1-9 need to be filled in in the spaces, so that each row, each column, and each 3×3 square contains exactly 1-9.
The basic method to solve the problem is the elimination method: look at what numbers already exist in the row, column, and grid where a certain space is located, eliminate the impossible, and the rest is the answer. Advanced skills include unique candidate numbers, implicit unique numbers, X-Wing, etc.
The difficulty ranges from simple to expert. Simple topics have many clues and direct reasoning, and expert topics have few clues and require complex skills. The page provides a note function that allows you to mark candidate numbers in the grid. Error detection highlights conflicting numbers.
In the online Sudoku game, fill in 1-9 in the 9×9 grid, so that the numbers in each row, column, and 3×3 grid do not repeat, supporting multiple difficulties.