Professional mathematics (Ph.D. level) long ago; nowadays only an amateur. My current employer does not actually prevent me from publishing but there is an administrative burden.

I am aware that my comments and answers on SE are of varying usefulness, quality and maths level. If you happen to find a contribution useful enough to quote it in a paper, feel free to cite me as "an anonymous user on math.stackexchange" or "user Justpassingby on math.stackexchange".