My MBTI tests have always returned INFJ results. I figured it couldn't be right, since it's supposedly a rare type, so I read several different descriptions of each type. I'm a real, legit INFJ. The descriptions were creepily accurate, and none of the other types were even close.
I do think I probably come off differently online than off, though that's just a guess. I'm always myself, but text will never be the same as spoken words.