Nonogram Sum is a free Chrome add-on developed by Antti Lehto. It falls under the category of Browsers and specifically belongs to the Add-ons & Tools subcategory. This handy tool is designed to enhance your nonogram-solving experience on the popular website, nonograms.org.

Nonogram Sum simplifies the process of solving nonograms by summing up the rows and columns, even if they contain spaces. This feature saves you time and effort, allowing you to focus on the puzzle itself. Additionally, the add-on provides a green background to indicate if it is possible to start filling in the nonogram using the overlap method.

To use Nonogram Sum, simply visit nonograms.org and select either the "Black & white" or "Colour" nonograms. With this add-on, you can streamline your nonogram-solving process and enjoy a more efficient and enjoyable puzzle-solving experience.