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Climb the Leaderboard.
Unlimited free puzzles across 9×9 Classic (six tiers from Easy to Evil), 6×6 Mini, 4×4 Kids, and the cage-based Killer Sudoku variant. Earn XP, level up, race friends on the same board. Sign in free to go ad-free and save your progress across devices — or jump in as a guest and start solving in seconds.
Track your streak, earn XP, climb the leaderboard, and challenge friends.
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Join the sudoku community
Free for everyone — no credit card, no email required. Pick a character, save your progress across devices, and climb the leaderboard.
All-time top players
All-TimeOne click with Google. No password, no card, no spam.
View full leaderboard →Unlimited puzzles across every mode
Classic 9×9 across six difficulty tiers (Easy → Medium → Hard → Expert → Master → Evil), plus 6×6 Mini, 4×4 Kids, and the cage-based Killer Sudoku variant. Every puzzle is mathematically unique and logic-solvable — no guessing, no downloads, no paywall.
Earn XP and level up
Every solve awards XP, with tougher difficulties paying more and a bonus for winning challenges. Master and Evil pay the most; Killer Sudoku counts toward the same XP ladder.
Build a daily streak
Solve one puzzle a day and your streak grows. Miss a day and it resets to 1. The flame next to your avatar tracks your consistency — keep it burning to climb the weekly leaderboard.
What's new
Three big upgrades, all live now
Killer Sudoku
Cages with target sums replace givens. Every digit in a cage is distinct and adds up to the cage total — the sudoku.com #2 mode, now on Sudoku247Online across four difficulty tiers.
Try Killer →New tierMaster & Evil
Two new difficulty tiers above Expert. Master sits at 18-19 givens with advanced technique territory; Evil ships at the proven 17-given floor for a real cognitive workout.
Climb the ladder →New controlShow Candidates + smarter hints
One tap fills every empty cell with its valid pencil marks. A new graduated hint menu offers Reveal Cell (1 hint), Reveal Box (3 hints), or free Show Candidates — every action is undoable.
Solve smarter →How to Play
Fill the Rows
Each row must contain every digit from 1 to 9 without any repetition.
Complete Columns
Every vertical column must also house all numbers from 1 through 9 once.
Solve the Box
Each of the nine 3x3 sub-grids must satisfy the same unique digit rule.
Take your logic to the tactile world.
Unlimited free printable sudoku — any grid size, any difficulty, 1 / 4 / 6 per page. No watermarks, no sign-up, no email.
Print Today's Puzzle
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Creating an account takes one tap. In return you get a fully ad-free experience, XP and levels that stick, cross-device sync, a global leaderboard, 1-vs-1 challenges with friends, and direct support when you need it. No email, no password, no credit card — ever.
Zero ads — signed-in only
Guests see sponsored banners; signed-in users get every page ad-free — board, leaderboard, print hub, everywhere.
Global leaderboard
All-Time and Last-7-Days tabs, ranked by XP, with country flags. Your row is highlighted when you're on it.
Friends by email
Send a friend request to any email address. If they already play, they get an in-app request. If not, we queue an invite for when they join.
1-vs-1 challenges
Pick a friend, pick a difficulty, both race on the exact same puzzle. Fastest finisher earns a bonus on top of the regular solve reward.
Direct support — new
Bug, missing streak, or a question? Open a ticket from the new Support page in your account menu. Replies typically within 24 hours.
One click with Google. No password, no card, no spam.
Strategy, tips and guides
Snyder Notation: The Sudoku Trick of World Champions
Most sudoku players who use candidate tracking write all possible numbers into every empty cell — a comprehensive approach that gives you complete information but can make the grid look cluttered and overwhelming. Snyder notation is a different approach: write fewer candidates, only in specific circumstances, and use that restraint to make patterns more visible…. Continue reading on Snyder Notation: The Sudoku Trick of World Champions
The Untold Sudoku History: From Indiana to the World
Sudoku is one of the most widely played puzzles in the world — published daily in thousands of newspapers, solved by millions of people on phones and tablets, and the subject of international championships. Yet most people who play it every day have no idea where it came from, who invented it, or why it… Continue reading on The Untold Sudoku History: From Indiana to the World
Stop Struggling with Sudoku: Master Candidate Mode Now
If you have ever stared at a hard sudoku puzzle and felt completely stuck, candidate mode is probably the tool you are missing. It transforms the way you see the grid — turning an overwhelming collection of empty cells into a structured map of possibilities. This guide explains exactly what candidate mode is, when to… Continue reading on Stop Struggling with Sudoku: Master Candidate Mode Now