As someone who frequently does the full and mini NYT crosswords, I really like this idea. I’ve wondered what it’d be like trying to make my own. This seems like a useful tool for giving it a try.

Some feedback: - The chart showing the distribution of word length is very cool. - Maybe you could educate newbies about how can choose a grid. I’m wondering if the predefined ones you provide are commonly seen in NYT. Does NYT prefer certain grids? Are you more likely to be accepted by NYT with a unique grid? - Custom grids sounds like a great feature. I’m guessing there are some rules about symmetry and no two-letter words that you can help users with. - Auto filling on an empty grid basically does all the work except clue writing? Maybe that’s intensive for your back-end? I noticed the page hang when submitting that. Maybe you can require some percentage for the user to first fill in on their own? As a user I think I’d only want the grid to highlight areas where I have an invalid word.