Noodler
Sudoku
One hard grid a day
A fresh hard Sudoku every day — no repeats, no giveaways. Fill every row, column, and box with 1-9.
A new puzzle unlocks daily at local midnight on your device — no account, no signup, and nothing to install. Progress and stats are saved locally in your browser, not on a server.
How to play
- Fill every row, column, and 3×3 box with the digits 1-9 — no repeats.
- Click or tap a cell, then type a digit or use the number pad below the board.
- Toggle Notes to pencil in candidate digits instead of committing to one — placing a digit for real automatically clears it from that digit's notes nearby. Auto Notes fills every empty cell's notes in one go.
- We'll flag a digit in red if it clashes with another in its row, column, or box — fix it and keep going. There's no limit on attempts.
Read the FAQ for more on how the daily puzzle works, or visit the blog for tips.
About Sudoku
I built this one because I could never find Sudokus with the right balance - most are either far too easy or brutal in a way that's not fun. Every grid here is checked to have exactly one solution and calibrated to sit right at "hard but fair."
The rules are the classic ones: fill every row, column, and 3×3 box with the digits 1-9, no repeats. If you want a hand with the harder grids, I've written up the techniques I use to solve them.
There's a new grid every day. I hope it's a good one to sit down with each morning.
Sudoku FAQ
Is there a limit on how many mistakes I can make?
No — there's no guess or life limit. A digit that clashes with another in its row, column, or box is flagged in red so you can fix it, but you can keep going as long as you like.
What do Notes do?
Notes let you pencil in candidate digits for a cell instead of committing to one. Toggle Notes on, tap in the digits you're weighing up, then toggle it off when you're ready to commit for real — placing a real digit automatically clears it from that digit's notes nearby. Auto Notes fills every empty cell's candidates in one go.
Does every puzzle have exactly one solution?
Yes — every grid is checked at generation time to have a single, unique solution, so anything you can rule out logically is always safe to rule out.
How hard are Noodler's Sudoku puzzles?
Every generated grid is graded for difficulty, and only the ones that land at "hard but fair" get published — enough bite to need real technique, without ever needing to guess.
Is there a timer?
Yes — your solve time is tracked and shown once you finish, and your fastest solve is kept in your stats.