Nonogram Solver Online
Paste the row and column clues from any Nonogram and this nonogram solver online fills every cell that logic can force — free, in your browser, nothing to download. It reports contradictions, and on boards up to 12×12 it counts how many solutions exist so you know whether the puzzle is unique. Stuck mid-game? This is the same line-deduction engine the Hint button uses, so you can watch the deduction you missed play out one step at a time. Prefer playing first? Open a live board on all sizes or home.
Paste clues, then Solve all or Next step.
Grid will appear here.
What is a Nonogram solver?
A Nonogram solver takes the number clues from a picture-logic puzzle and works out which cells must be filled and which must stay empty — without you having to reason through the grid by hand. Clues describe runs of filled cells: a row reading 4 2 means a block of four, at least one gap, then a block of two, in that order.
The solver compares every row clue against every column clue and keeps only the cells that hold up in every valid arrangement. Repeat that until nothing new can be forced, and you have either the finished picture, or a clear signal about why the clues don’t add up.
People reach for a solver for four different reasons, and this tool handles all of them:
- You’re stuck on a real puzzle and want to know which line to look at next, without being handed the whole answer.
- You’re checking a puzzle you made and need to know whether it has exactly one solution.
- You’re learning the technique and want to read the deduction one move at a time.
- You typed clues in and got nothing and need to find out whether the mistake is yours or the puzzle’s.
The rules are identical across Picross, Griddlers, Hanjie, Japanese crossword and picture cross — so a Nonogram solver solves all of them. See what is a Nonogram and Nonogram vs Picross for why the names differ while the puzzle doesn’t.
How to use this Nonogram solver
- Copy the row clues. One row per line, numbers separated by spaces, top row first. A row with no filled cells can be left blank or written as
0. - Copy the column clues. One column per line, left column first, same format.
- Press Solve all to fill every cell that logic can force in one go.
- Or press Next step to apply a single deduction. The log tells you which line was narrowed and why that cell could not be anything else.
- Work in short bursts. Hit Next step a few times, then go back to your own puzzle with the technique you just watched, rather than clicking all the way to the answer.
- Press Load sample if you want to see a full run before typing your own clues — it loads a small board you can step through.
Both clue boxes accept pasted text, so you can lift the numbers straight out of a puzzle book, a screenshot you typed up, or the clue panel of our generator. Bad input doesn’t fail silently: lines that can’t be parsed are flagged rather than ignored, because a typo in one clue is the most common reason a perfectly good puzzle appears to have no solution. For more on reading numbers, see how to read Nonogram clues.
Reading the clues you paste
Each number is the length of one run of filled cells. Runs appear in the order listed, and two runs on the same line must be separated by at least one empty cell. Spaces before the first run and after the last one can be any length, including zero — that freedom is exactly what makes deduction possible.
5in a five-wide line fills every cell. Nothing to work out.1 1is two single cells with at least one gap between them.0or a blank line means nothing is filled in that line.4 2is a block of four, a gap, then a block of two.
Clue order never changes, and that’s the whole guarantee. It’s also why 2 4 and 4 2 are different puzzles.
Reading the step log
Most solvers just show you the finished grid. This one shows its work — and that’s the part that teaches you something.
Every line in the log names the row or column it worked on and states the deduction in plain words: the remaining placements for that line all cover these cells, so they are filled; or no remaining placement covers this cell, so it is empty. The grid highlights that line as a scanner bar; a red highlight marks the first contradictory clue. Step through it slowly and you’ll start recognising the same patterns on paper. The two that come up constantly:
- Overlap. If a block is longer than half the line, the cells covered by every possible position of it must be filled. A block of 3 in a five-cell line forces the middle cell; a block of 6 in a ten-cell line forces cells 5 and 6.
- Edge counting. Slide the blocks as far left as they go, then as far right. Anything covered in both extremes is forced. Same idea as overlap, but it also works on lines with several blocks.
This is the same engine as the in-game Hint, so if a live board stumped you, paste its clues here and read the deduction you missed. If you’d rather build the habit from scratch, How to Solve Nonograms lays out the full routine.
Why a puzzle can have no solution, or more than one
Two failures look identical to a player but have different causes — and telling them apart is what a solver is really for.
No solution. Almost always a typo, or clues that describe different amounts of ink. Add up all the row clues, then all the column clues: the two totals must match, because both count the same filled cells. If the rows add to 32 and the columns to 30, no grid can satisfy both, and the solver will stop and say so instead of guessing. The other common cause is a clue entered out of order — 3 1 typed as 1 3.
More than one solution. The clue set is balanced but ambiguous: two or more different pictures fit every clue. On boards up to 12×12 this solver counts the solutions and reports the number, so you know where you stand. A published puzzle should have exactly one, because uniqueness is what lets you progress by logic instead of guessing. If a puzzle you made comes back with several, the clues need tightening — add a filled cell or split a block, then run the check again in the Nonogram generator.
A single-valued answer doesn’t automatically mean the puzzle is nice, though. Clues can be unique and still require a guess partway through. If the forced-logic stage runs out of moves, the log says so plainly rather than pretending the grid is finished — that’s your signal that a human solving this board would have to guess.
Solver, Picross, Griddlers, Hanjie — one tool for all of them
The rules don’t change with the name, so the solver doesn’t either. Picross is the name Nintendo’s games gave the puzzle and the one most English-speaking players type; Nonogram is the general international term; Hanjie is what British puzzle books used; Griddlers spread through puzzle magazines; picture cross and pixel cross turn up in app stores. Feed any of them in and you get the same grid out — this page is a free picross solver for the puzzle type as well as a Nonogram solver.
There is one thing this tool is not: an official Picross solver for Nintendo’s titles. It works on the puzzle type, not on a specific game’s boards or save files. Full naming history is in Nonogram vs Picross. Want to play instead of check? Open Picross online.
Using the solver to design and check your own puzzles
The solver is as useful for making puzzles as for solving them. Draw your picture, turn it into clues, then paste those clues back in and check the result — a design that’s meant to be solvable by logic should come back unique and fully forced.
A short quality checklist we use on our own boards:
- Row and column clue totals match. If they don’t, the puzzle has no solution at all.
- The answer is unique. More than one solution means the clues are ambiguous — tighten them.
- Forced logic finishes the grid. If it doesn’t, the player has to guess somewhere, which most solvers hate.
- Re-check after every edit. Changing one cell in the picture changes clues in two lines at once.
Our Nonogram generator / maker produces a picture and its clues together, and this solver is the step that verifies them before anything gets shared. If you’re heading to paper instead, Printable Nonograms gives you a sheet you can solve offline — and this page is the way to pre-check it before you hand it to a class.
Solve it by hand first
Worth saying plainly: the solver is a safety net, not the game. Nonograms are designed to be cracked by deduction, and the two ideas that carry almost every board are filling the longest runs first and using overlap to force the middle. A solver you reach for after ten honest minutes teaches you something; one you reach for at minute one teaches you nothing.
Better sequence: try the board, get stuck, read one Next step, go back and apply that pattern yourself. If you want the full technique set, How to Solve Nonograms and the overlap method are the two pages to read next. Nonogram strategies goes deeper when those feel automatic.
Nonogram Solver FAQ
Is this Nonogram solver free?
Yes — no account, no download, no limit on how many puzzles you check.
Does it work on Picross and Griddlers puzzles?
Yes. Same clues, same gap rule, so the same solver handles Picross, Griddlers, Hanjie, Japanese crossword and picture cross puzzles.
Can it solve a Nonogram from an image or a photo?
Not directly — you type the clues in. There’s no reliable image-to-clues reader here, so copy the numbers from the original puzzle or the screenshot; a misread digit is the fastest way to a false “no solution”.
Can I solve a puzzle from a photo of a paper sheet?
Same answer: transcribe the clues first. Once they’re in, the solver doesn’t care where they came from.
Why does it say there are multiple solutions?
More than one grid satisfies your clues. The answer shown is valid, but the clue set isn’t unique — common in handmade or poorly tested puzzles.
Why does it say there’s no solution?
Usually a typo. Check the row and column clue totals match, and re-read each line against the original — an out-of-order clue is the usual culprit.
Does it do step-by-step solutions?
Yes — Next step applies one forced deduction at a time, Play steps walks the same deductions with a moving scanner bar, and the log explains each line in words. That’s the difference between copying an answer and learning a technique.
Can it solve color Nonograms?
No. This solver handles black-and-white clues only. Colored puzzles need per-color clue sets, which is a different engine.
Does it work on mobile?
Yes. The clue boxes and grid are responsive, though entering a 20×20 by hand is easier on a wider screen.
Is this an AI solver, or should I ask ChatGPT instead?
It’s a deductive solver, not a language model — it never guesses and never invents an answer. Every cell it fills is forced by your clues, and when the clues don’t determine the grid it tells you so instead of producing something plausible-looking.
Keep solving
Ready to play instead of check? Start on a board and use the Hint only when you’re genuinely stuck.