Every question
has an answer —
just like sudoku.

The short version: a free sudoku site that opens straight in your browser — no account needed. On top of classic nine-by-nine puzzles, there's a daily sudoku, competitive mode, and printable puzzles. Available in English and several other languages.

Fill a nine-by-nine grid with the digits one through nine so that each digit appears exactly once in every row, every column, and every three-by-three box. No maths involved — it's pure logic and elimination. Every puzzle has one and only one correct solution.

For a proper walkthrough, head to the Guide page.

Free. Competitive mode, daily sudoku, leaderboard, game coach — all of it, no strings attached.

There are several languages to choose from. Switch via the language menu at the top of the page and the whole interface updates.

Works on phones and tablets with nothing to install. Cell selection and number input on touchscreens have each been tuned independently.

Three levels: easy, medium, and hard.

Easy starts with more cells filled in — good for getting the hang of the rules. Medium takes a bit more thought. Hard is genuinely hard; some puzzles won't budge without techniques like X-Wing. Hit New Round to start a fresh game.

Sudokum.net is fully keyboard-controllable:

• ↑ ↓ ← → — move between cells
• N — toggle notes mode (jot down candidates)
• H — apply a hint to the selected empty cell
• 0 / Del — clear a cell's value or notes
• Backspace — undo the last move

Press N to enter notes mode and pencil candidate digits into a cell in small type. It keeps track of which numbers could go in a given spot — at hard difficulty, trying to progress without notes is a real slog.

Select an empty cell and press H — it fills itself in. Handy in a pinch, but each hint dents your score. Use them sparingly in competitive mode.

The error counter at the top ticks up by one. You can undo with Backspace — no need to start over.

The header shows live time, errors, and score. Your score only drops for two reasons: mistakes and hints. Keep both at zero and you'll max it out. That's all there is to it.

A side panel that watches your game and offers guidance. It has three modes:

• Silent — completely hands-off, play entirely on your own terms.
• Balanced — gives a gentle nudge when you're stuck.
• Teaching — names the technique that applies to the selected cell. This is where you pick up real sudoku vocabulary, like "candidate elimination".

Beginners are better off keeping teaching mode on for a while — once the logic clicks, turn it off.

Every day at midnight UTC. Players worldwide solve the same puzzle, so the results are directly comparable. Refresh the page to see the new one.

Sudokum.net's content section. Head to /sudohub for articles on sudoku techniques and strategy.

Click the theme button in the top-right corner and it swaps instantly. Dark mode is easier on the eyes for longer sessions — but it's your call.

The Game Coach panel updates your completion percentage live. It also shows the row and column info for whichever cell you've selected.

Everyone solves the same puzzle, your time gets logged, and the result goes on the leaderboard. The aim is to finish the hard puzzle as fast as you can. Check the rankings page to see where you stand.

Players are ranked by total score. Playing regularly pushes your position up. Check the Rankings tab in the top menu.

Type whatever name you want into the Player name field on the game screen. That's what shows up on the leaderboard.

Don't make mistakes, don't use hints, and pick the hard level — do those three things and your score will climb on its own. Skipping the daily sudoku also hurts your ranking.

Check the Terms of Use page — the season length and reset schedule are explained there.

Yes. Don't close or refresh the page before you finish — especially in competitive mode.

Any up-to-date modern browser, no extensions needed. Running into issues on an older browser? Updating it should sort things out.

Use the Contact link in the footer. Bug reports, feature requests — all of it goes there.

Links to the Privacy Policy and Terms of Use are in the footer. Cookie details and data usage are covered there.

Yes. Go to Printable Sudoku in the main menu, choose a difficulty, and print. Great for travelling, offline use, or anyone who prefers pen and paper.

Yes, at /kids. Instead of the standard nine-by-nine grid, it uses smaller grids with age-appropriate puzzles.

Yes. The print option in the kids section includes puzzles designed with children in mind. They print cleanly on A4 and work perfectly well in black and white. They're also suitable for classroom activities.

The general consensus is yes. It has a positive effect on logical thinking, focus, and patience. Since no arithmetic is involved, kids who struggle with maths can still take part without any trouble. The fact that it demands active thinking rather than passive screen time is a bonus.