Play Sudoku Online, Free

A clean, fast Sudoku you can play right in your browser. Pick a level, fill the grid, and track your time. No download, no sign-up, no Flash.

What is Sudoku?

Sudoku is the world's most popular number puzzle, and its appeal comes from how little you need to start. There is no arithmetic, no trivia and no luck. The board is a 9×9 grid divided into nine smaller 3×3 boxes. A handful of numbers are printed at the start, and your job is to complete the rest using logic alone. Because every puzzle on this site is generated with exactly one solution, you never have to guess. If you are stuck, there is always a next step waiting to be found.

The puzzle was popularised in Japan in the 1980s, where it took the name sudoku, roughly "single number", and it spread around the world in the mid-2000s. Today it is a daily habit for millions of people who use it to relax, to sharpen their focus, or simply to fill a few quiet minutes. You can do the same here, on any device, without installing anything.

The rules in one minute

There is only one rule, applied three ways. Fill every empty cell with a number from 1 to 9 so that:

• each row contains all nine numbers with none repeated;
• each column contains all nine numbers with none repeated;
• each 3×3 box contains all nine numbers with none repeated.

That is the whole game. When those three conditions are met across the board, the puzzle is solved. Everything else is a matter of finding the order in which the numbers reveal themselves.

How to solve: the core logic

Good solving is a search for cells where the answer is forced. The simplest pattern is the naked single: a cell where eight of the nine numbers already appear in its row, column or box, leaving only one legal choice. Scan for these first, because each one you place removes options elsewhere and often triggers a chain of further placements.

The next pattern is the hidden single: a number that can legally go in only one cell of a particular row, column or box, even though that cell looks like it has several candidates. Spotting hidden singles is the skill that carries you from easy puzzles into medium ones. Beyond that lie pairs, triples and more advanced eliminations, which come into play on the hardest boards.

A reliable habit is to work unit by unit. Pick a row, column or box that is already nearly full and finish it, then move to the next. Pencil notes help enormously here. By writing the possible numbers into each empty cell, you turn a vague grid into a map you can reason about.

Everything this Sudoku can do

This is a full-featured game, not a static grid. While you play you can:

• Take pencil notes. Toggle notes mode and mark the candidates for any cell, exactly as you would with a pencil on paper. Placing a real number automatically clears it from the notes of every cell it affects.
• Ask for a hint. When you are stuck, reveal the correct value for a single cell and keep going.
• Learn with Training. Training mode does more than hand you an answer. It explains the next logical step, names the technique behind it, and lets you apply it, so you improve instead of just finishing.
• Undo and redo freely, erase mistakes, and pause the clock whenever life interrupts.
• Track your progress. The Stats screen records your solve times, mistakes, hints used and win rate for each difficulty, so you can watch yourself get faster.

Your game is saved automatically in the browser, so you can close the tab and return to the same board later. A light and dark theme, full keyboard support and a responsive layout mean it plays well on a phone, a tablet or a desktop.

Three difficulty levels

Every board is generated fresh, so you never replay the same puzzle. New players should start with Easy Sudoku, which gives more starting numbers and gentler logic. Medium removes some of those clues and rewards careful note-taking, while Expert strips the board back to the minimum and calls for advanced technique. Moving up one level at a time is the fastest way to improve.

More than one kind of Sudoku

Once the classic grid feels familiar, the same logic opens onto a whole family of puzzles. Color Sudoku replaces the numbers with nine colours for a calmer, more visual solve. Killer Sudoku adds arithmetic cages that must sum to a target. Flower Sudoku swaps the nine boxes for colourful jigsaw petals, and Chain Sudoku offers a lighter, quicker puzzle on a grid of linked circles. Each one is free, needs no download, and plays right here in your browser.