I can't even figure out what Stainless does (did)

It turned API specs into ssoftware devolopment kits and model context servers. Basically connecting existing tools to AI agents so they can actually use them.

They might be a big part of the reason why claude code can edit notion docs for you pretty easily

do they have one of those websites that looks like all of those websites

edit: they sure do

Nothing (AI slop to create an unnecessary product, funded by A16Z).