About nonograms.io

The home of nonograms. nonograms.io is a free nonogram site: a daily puzzle, five board sizes from 5×5 to 25×25, and live co-op rooms, in your browser.

Nonograms are picture logic puzzles: numbers beside and above a grid tell you which squares to fill, and a picture appears when you get them right.

A puzzle worth coming back to every day, and people to solve it with: that's what we're building.

New to them? Read how to play, or pick a board from all sizes.

What you can do here

Play any size. Boards run from 5×5 to 25×25, at easy, medium, hard and expert.
Do the daily puzzle. Everyone gets the same board on the same date, 10×10, 15×15 or 20×20 depending on the weekday. It's the one to compare notes on.
Solve with friends. Create a room, send the link, and everyone paints one board together, live.
Take it at your own pace. There is undo and redo, and a hint that points to a row or column with a forced move. By default a wrong square is marked as soon as you place it; if you would rather find mistakes yourself, pick "Only when I press Check" in Settings and use Check, which counts the wrong squares without showing where they are. Your progress and settings stay in your browser.

How every puzzle is checked

Every puzzle we serve is made by our own generator, and our solver works through it before it is accepted. The same check runs on every board, whether it comes from the daily puzzle, quick play or a room. Here is what the solver checks, by difficulty.

Easy, medium and hard are accepted only if line logic alone solves the whole board. Line logic looks at one row or column at a time and fills or crosses every square that is forced, given the clue and what is already marked. It repeats across rows and columns until nothing is left to do. If that finishes the grid, the board has exactly one solution and never needs a guess.
Expert boards are rejected if line logic alone finishes them. They are accepted only if line logic plus contradiction probing does. Probing means testing a square: assume it is filled, follow line logic, and if that runs into a contradiction, the square must be empty (and the other way round). Every step is a proof, so an expert board still has exactly one solution and is still solved without guessing. It just needs lookahead.
Difficulty is measured, not guessed. The solver records how the solve went, such as how many sweeps it needed and how much it could fill on the first pass, and the board lands in a difficulty band for its size from that score.

These checks describe the puzzles we serve, made by our generator. Boards from anywhere else have not been through them.

Contact

Found a puzzle that feels wrong, a bug, or an idea you want to share? Write to us. nonograms.io@gmail.com

About nonograms.io

The home of nonograms. nonograms.io is a free nonogram site: a daily puzzle, five board sizes from 5×5 to 25×25, and live co-op rooms, in your browser.

Nonograms are picture logic puzzles: numbers beside and above a grid tell you which squares to fill, and a picture appears when you get them right.

A puzzle worth coming back to every day, and people to solve it with: that's what we're building.

New to them? Read how to play, or pick a board from all sizes.

What you can do here

Play any size. Boards run from 5×5 to 25×25, at easy, medium, hard and expert.

Do the daily puzzle. Everyone gets the same board on the same date, 10×10, 15×15 or 20×20 depending on the weekday. It's the one to compare notes on.

Solve with friends. Create a room, send the link, and everyone paints one board together, live.

Take it at your own pace. There is undo and redo, and a hint that points to a row or column with a forced move. By default a wrong square is marked as soon as you place it; if you would rather find mistakes yourself, pick "Only when I press Check" in Settings and use Check, which counts the wrong squares without showing where they are. Your progress and settings stay in your browser.

How every puzzle is checked

Easy, medium and hard are accepted only if line logic alone solves the whole board. Line logic looks at one row or column at a time and fills or crosses every square that is forced, given the clue and what is already marked. It repeats across rows and columns until nothing is left to do. If that finishes the grid, the board has exactly one solution and never needs a guess.

Expert boards are rejected if line logic alone finishes them. They are accepted only if line logic plus contradiction probing does. Probing means testing a square: assume it is filled, follow line logic, and if that runs into a contradiction, the square must be empty (and the other way round). Every step is a proof, so an expert board still has exactly one solution and is still solved without guessing. It just needs lookahead.

Difficulty is measured, not guessed. The solver records how the solve went, such as how many sweeps it needed and how much it could fill on the first pass, and the board lands in a difficulty band for its size from that score.

These checks describe the puzzles we serve, made by our generator. Boards from anywhere else have not been through them.