Free Online Sudoku — Easy to Expert, No Download, No Forced Ads
Play Sudoku free in your browser on phone or desktop. Every puzzle is guaranteed to have exactly one solution, solvable by pure logic — no guessing, ever. Four difficulty tiers plus a fresh daily puzzle, pencil notes, smart highlights, and an honest one-time Pro unlock. No app, no signup, near-instant load.
How to play Sudoku
The goal is to fill the 9×9 grid so that every row, every column, and each of the nine 3×3 boxes contains the digits 1 to 9 exactly once. The puzzle starts with some cells already filled (the "givens"); the rest are yours to deduce. Tap an empty cell, then tap a number on the pad to place it — tap the same number again or use Erase to clear it. Toggle Notes (pencil marks) to jot candidate digits in a cell before you commit. There is no time limit and no way to lose: take as long as you like.
Solving techniques (from beginner to expert)
- Naked single: a cell where only one digit can legally go — fill it.
- Hidden single: a digit that can only fit in one cell of a row, column or box, even if that cell could in theory hold others.
- Pointing pairs / box-line reduction: when a digit in a box is confined to one row or column, eliminate it from the rest of that line.
- Naked & hidden pairs/triples: two or three cells in a unit that together can only hold the same two or three digits — remove those candidates from the unit's other cells.
- X-Wing and advanced subsets: grid-spanning patterns that let you eliminate candidates across rows and columns. Our Expert puzzles can require these, but never a guess.
Why this Sudoku is fair
Because every board is generated with a uniqueness-checking solver, each puzzle has one and only one answer and can always be finished by logic alone. The mistakes counter is just a stat — there is no "three strikes and you lose" and no pay-to-continue. The whole game is free forever: all four tiers, the daily puzzle, notes, conflict highlighting, 10 undos and 3 hints per puzzle. The optional Pro unlock removes the single footer banner and adds unlimited undo/hints, auto-pencil, dark mode and detailed stats — comfort and looks, never the ability to win.
Frequently asked questions
Is it really free?
Yes. Every difficulty, the daily puzzle, notes, highlights, undo and hints are free forever. A single restrained footer banner keeps the lights on; one optional $4.99 Pro unlock removes it and adds convenience features.
Do I need to create an account or download anything?
No. It runs entirely in your browser. Your in-progress puzzle, stats and streak are saved locally on your device.
Can every puzzle be solved without guessing?
Yes. The generator guarantees exactly one solution and grades each puzzle by the hardest logical technique required, so you can always deduce your way to the answer.
What is the Daily Puzzle?
One shared board, the same for everyone in the world each day, at a medium-to-hard difficulty. Finishing it extends your daily streak, and you can share a spoiler-free result.
How do pencil notes work?
Turn on Notes, then tap digits to pencil in candidates in a cell's mini-grid. Placing a final digit can auto-remove that candidate from neighbouring cells. Pro players can auto-fill all legal notes with one tap.