is there any rest apis of any kind?
this question was asked back in 2014, back then seems the answer was "no, but it most likely will end up in the 3.2.x line", ref
viewtopic.php?f=71&t=2246946#p13648086
(specifically i'm looking for an api to ask "is this username already taken?" and "is this a legal username?", but i'll take that in another thread if need be)