Online Crossword Puzzle Generator

This page describes how the online crossword generator within Puzzel.org works.

The crossword puzzle maker itself plus additional info about all of the features can be found here:

Crossword puzzle maker

The base of any crossword puzzle is the intersection of words, hence the name 'crossword'. The goal of the crossword puzzle generator therefore, is to make sure words are crossed in the best possible way.

There are all sorts of ways to generate the 'best' way, but I will describe on this page how I went about building the crossword puzzle algorithm within Puzzel.org

To generate a crossword puzzle towards the 'best way', we need to have some sort of check in place that determines if a crossword puzzle is looking good or not.

To simplify this problem, I have chosen to split this challenge up into two different analyses:

• The number of intersections per word
• The number of surrounding black squares

To optimize the number of intersections, the algorithm tries as many word combinations as possible. But this can be made smarter, since the crossword generator knows which words have overlap on certain characters and which words don't.

For each list of words that have overlap with another list of words, the generator will start calculating the maximum number of intersections it can find, while placed in an imaginary puzzle grid.

By creating thousands of these imaginary grids, the algorithm has quite some options to work with and to find different kinds of solutions that have optimised for intersection.

The best outcomes from the crossword generator, are then checked for the next value, namely the number of black squares that remain in the puzzle grid.

The assumption here is, that less black squares mean more compact crossword puzzles and thus the crossword puzzle generated looks prettier.

Since the crossword generator does not have unlimited calculating power (it all happens from within your browser) and it has imperfect input to work with, namely words that do not perfectly intersect together, it will never beat the crossword puzzles that you see in the newspaper.

The crossword puzzle generator does its best to come close to a crossword puzzle that is as pretty as possible, but manual labour will always win since handpicked answers that exactly fit a certain spot is currently a skill fit for the human only.

Since you are probably a human, you can enter the generator challenge though! Puzzel.org provides the manual crossword puzzle maker as well, to which you can switch at any point during the building process.

You can switch to it via the black/white human head icon at the top-right of the crossword puzzle preview, when working in the crossword puzzle maker.

This will allow you to add certain small words in some of the gaps for example, which will improve the compactness of your crossword puzzle drastically in a way that the automated crossword puzzle generator would never be able to realize.

Go to the crossword puzzle maker