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Nonogram Builder logo: stylized brick letter N symbol over the square picross puzzle playing field.

Nonogram Builder: Create Your Custom Nonogram Online

Create custom puzzles with the comprehensive online builder featuring multi-step workflow. The tool is built for designing pixel nonogram challenges, generating automatic number hints, and exporting professional picross games. It handles square grid layouts from size of 5 up to 50, supports real-time hint validation, and provides instant puzzle preview. You can convert images to griddlers or paint from scratch with build-in tools including zoom, shift assistance, and undo functionality. When finished, export to image and JSON format.

Introduction

Nonogram Builder is a browser-based nonogram (picross / griddlers) authoring suite that helps you convert images into playable puzzles, paint grids by hand from scratch, and export finished results so you or anyone else can try solving them. It’s designed for puzzle authors, educators, and hobbyists who are interested in creating their own nonograms.

How Hard is the Nonogram Creation

Creating a valid nonogram requires converting an image into a strict pixel grid, cleaning noise, generating accurate numeric hints, and ensuring the puzzle has a valid (ideally unique) solution. Manual workflows are slow and error-prone. Nonogram Builder automates the heavy work — image conversion, hint generation, and export — while giving you basic editing tools for polish. What it does not do — solvability or complexity testing; that is a job for a separate tool.

Core Features

Create From Scratch

  1. Paint your solution over the grid, adjusting the filled squares as necessary.
  2. Use tools over the grid to manipulate the grid and its appearance.
  3. Press the Export button and follow the export steps.
  4. Review your puzzle, then press "Download as PNG".
  5. The puzzle will be in your device's Downloads folder.
  6. Share, print, or play right on your device.

Create From Custom Image

  1. Press "Use Image" and choose your starting image.
  2. Use toolbar controls to adjust your grid size and image properties.
  3. If necessary, crop your image by using the optional "Crop" step above.
  4. Apply and proceed to the "Paint" step.
  5. Follow the same steps as for creating a nonogram from scratch.
  6. Go back to the image at any time to reset your starting solution.

Create From Other Nonogram

  1. Press "Use Image" and choose an image of your other solution.
  2. Switch to the "Crop" step and crop your image so it fits perfectly without hints or surrounding decorations.
  3. Confirm cropping and proceed to the "Pixelate" step.
  4. Count the number of original squares and set the grid size on the toolbar to match.
  5. Adjust the contrast slider until the pixelated preview shows your solution as closely as possible to the original.
  6. Apply and proceed to the "Paint" step.
  7. Follow the same steps as for creating a nonogram from scratch.

About

This tool is developed by Max Jakeins for the RenderSnail tools collection.

Feel free to report any problems or suggest fixes and features — just let us know.