Has is used ONLY with third person singular: he, she, it.
I have, you have, we have, they have, he has.
In normal speech, "anybody" would take the third person singular: If anyone has a converter, could you ...
However, as CB says in the post above yours, once you have a form of "to do" ("Does anybody..."), you use the base form of the verb: have.
He swims. Does he swim?
He has it. Does he have it?
She has one. Did she always have it?