I'm a camp director, and I've never heard of this one before (thanks!) It shows 500+ options, but they are all the individual sessions of larger camps- Smithsonian Associates has 108 camps listed. It's interesting that it shows whether a camp is full, since you typically need an account on their registration site to track that.

I submitted my camp and it doesn't have sections for area/age/grade/price, so they must either do a follow-up communication or have a bot trawl our website.

I like that they don't do sponsored camps, but I wonder what their model is. Seems weird to have a dedicated site for this that makes no money and doesn't require registration to collect visitor data.

CampsRock! is another big one. Local magazines or publications like DC City Paper, Montgomery Magazine, Baltimore's Child, Baltimore Family Alliance, and the Banner tend to have solid summer directories.

I think it’s biased. I put in basketball camps and it showed me Bullis and Sidwell as the only ones.
Is the website run by private schools by chance?

In case anyone is looking for summer camps in the area, I just came across this website that helps you find options by area, age, and price range: https://thrive-dmv.com/camps