Free, open-source, no ads

Play Free Online Sudoku

Free online sudoku means playing the classic 9×9 number puzzle in a browser or app with no purchase, install limit or paywall, and Suuudokuuu is a free, open-source implementation of it — six difficulty levels from Newbie to Hell, technique-explaining guides, no ads and no tracking in the game. Solve on the web or install the app, then keep the same streaks and stats everywhere. See why Suuudokuuu is built this way for the full, verifiable case.

Why players stay

• Six difficulty levels from Newbie through Hell, including a bundled 17-clue Hell corpus
• Technique-aware hints that name the exact solving pattern, not just the next digit
• Every puzzle guaranteed to have exactly one solution, no guessing required
• No ads, no account and no tracking inside the game, on the web or in the app
• Works fully offline once installed, on iOS, Android and the web
• Shareable puzzle links and full game replays for any solve

Learn to solve

Every technique Suuudokuuu uses to generate hints is documented with a worked example board pulled straight from the solving engine. Start with the full technique index, or jump into one of the first patterns most players learn.

• Full House — the simplest possible move, filling the last empty cell in a unit.
• Naked Single — a cell left with exactly one candidate.
• Hidden Single — a digit that only fits in one cell of a unit.

Stuck on a puzzle?

Type or paste the grid into the step-by-step sudoku solver and it will name every move — Hidden Single, Naked Pair, X-Wing — instead of just filling the board in. It checks that your puzzle has exactly one solution first, and it runs entirely in your browser.

New to Sudoku?

Read the how to play guide for the three rules and a walkthrough of your first moves, or look up any term in the sudoku glossary, which defines every technique and every piece of vocabulary the guides use.

Difficulty guides

Every tier from Newbie to Hell now has its own guide, breaking down exactly what separates one level from the next — clue counts, required techniques and an honest read on how hard each one really is. Start on the Sudoku difficulty levels hub, or see how it compares to the hardest puzzles ever published.