Pick a difficulty
Choose easy, medium, hard, or expert from the row above the board.
Free online Sudoku
Play Free Online Sudoku
Choose from four difficulty levels and start playing—no signup required.
See how to play
How it works
Simple controls for a classic puzzle.
Fill the grid
Use the number pad or keyboard. Turn on Notes when you want candidate marks.
Check or finish
Use Check to catch mistakes, Hint when stuck, and New Game for a fresh board.
Sudoku guides
Learn the rules, then solve with confidence.
Use a short guide when you want a clear next step away from the board.
How to play Sudoku
Learn the row, column, and 3×3 box rules without guessing.
Read the rulesSudoku tips for beginners
Scan with purpose, keep useful notes, and recover when you get stuck.
Explore beginner tipsVerified Sudoku techniques
Study twelve verified topics, from Singles and notes through Pairs and Triples to X-Wing, XY-Wing, and Swordfish.
Open the technique centreSudoku solver with explanations
Check solution count and replay each supported, verified logical step without uploading your puzzle.
Open the solverPrintable Sudoku PDFs
Print four verified daily puzzles in easy through expert levels, with separate answer pages.
Open printable puzzlesTransparent method
What makes one Sudoku harder than another?
Legen Difficulty Index uses verified techniques, weighted logical steps, and candidate eliminations—not clue count alone. This describes the reference corpus; the published home deck above follows a fixed rotation and is not assigned an LDI score.