nitpickiest

/ˈnɪtˌpɪkiɪst/
adjective
  1. Most inclined to find or complain about small, unimportant faults; extremely critical of minor details.
    • She is the nitpickiest person I know, always pointing out dust specks no one else sees.
    • Of all the editors, he was the nitpickiest, demanding every semicolon be perfect.
    • The nitpickiest customer complained that the font size was off by one pixel.