nitpicker
/ˈnɪtˌpɪkər/
noun
- A person who finds or complains about small, unimportant faults or details, often annoyingly.
- Don't be a nitpicker; the project is good enough as it is.
- My uncle is such a nitpicker that he once complained about the way I folded the napkins.
- The teacher was known as a nitpicker who would deduct points for tiny spelling errors.