Right now, the region filter doesn't seem to work. For example, if I click on iOS and San Francisco, I still see Kickstarter, Venmo, and Birchbox which show they are based in New York.

Also, I'm surprised that What Tech wasn't listed on its own site. :)

I'm also a fan of builtwith.com and trying to understand if you're doing the same thing or have a different objective.

P.S. I think the UI is super clean and very easy. Great job there.