Zaney Sudoku — free killer sudoku, classic sudoku, Sudoku X and Hyper Sudoku puzzles with daily challenges
1.7 million puzzles.
Zero dead ends.
Zaney Sudoku is a free online sudoku site with over 1.7 million puzzles across four games — killer sudoku, classic sudoku, Sudoku X and Hyper Sudoku — every one machine-verified to have exactly one solution before it reaches your screen. Killer is the main event, with five difficulties from Easy up to Nightmare. There are four daily puzzles, and classic sudoku includes a true beginner mode that teaches the game one step at a time.
Puzzle numbers are permanent: #4,821 on Hard is the same puzzle for everyone, forever. Send a friend the link and race them.
Want a different flavour? Sudoku X and Hyper · classic sudoku for beginners.
Sudoku X
Classic rules plus one elegant twist: both shaded diagonals must also hold 1–9. The centre cell sits on both — start there.
Hyper Sudoku
Four extra 3×3 windows, shaded on the grid, each holding 1–9. Thirteen boxes' worth of constraints on one grid.
Every variant puzzle is verified for a unique solution, prints with its shading, and shares by permanent number.
Coward's Sudoku
No cages. No sums. No shame. Classic sudoku for people who looked at killer and said "absolutely not" — starting with a mode so gentle it teaches you the game as you play.
Never played sudoku? Three rules: every row has the digits 1–9 once, every column has 1–9 once, and every 3×3 box has 1–9 once. That's the whole game.
Every Coward's puzzle is verified to be solvable one obvious step at a time — at any moment there's always a cell with only one possible digit. No guessing, no techniques, no shame in tapping 💡 Hint to have it pointed out. When it starts feeling easy, Classic Easy is next — and when you're ready for the real thing, killer sudoku awaits.
Your stats
| Mode | Solved | Best | Average | Effic. |
|---|
Efficiency is how many digits you typed versus how many blanks the puzzle had — 100% means you never overwrote a cell. Par times shown on the win screen are our own target benchmarks for each difficulty, not other players' times (nothing you do here is sent to a server).
Stats live in this browser only — no accounts, no servers.
Daily archive →Moving devices?
Copy a backup code here, then import it on your new phone or laptop to bring your streaks and stats with you.
Daily archive
Missed a day? It's still here. Streaks only count same-day solves, mind.
Solutions
This corner is for the truly defeated. Password required.
How to play killer sudoku
Killer sudoku is normal sudoku with one twist: there are no given digits to start from (mostly). Instead, the grid is carved into dashed cages, and each cage tells you what its digits add up to.
The rules
- Every row, column and 3×3 box contains the digits 1–9 exactly once.
- The digits inside each dashed cage add up to the small number in its corner.
- A digit can't repeat inside a cage.
Three tips to get you started
Where do 1.7 million puzzles come from?
Every puzzle number is dealt deterministically from its number — the same number always produces the same puzzle, on any device. As it's dealt, a solver verifies the puzzle has exactly one solution before you see it. That applies across every game: killer (all the way up to Nightmare), classic (including Coward's), Sudoku X and Hyper. No broken puzzles, no ambiguous endings.
Controls
- Arrow keys move around the grid, 1–9 places a digit.
- Hold Shift with a digit (or toggle Notes) for pencil marks.
- Backspace erases, U undoes, N toggles note mode, Space pauses.
Go deeper
Three guides live alongside the game: a complete beginner's guide, the cage combinations cheat sheet (every sum, every cage size, forced combos highlighted), and the strategy guide covering the rule of 45, innies and outies.