We hear them most often called "Grammar Nazis." But what we have a colloquial term for (at least, colloquial to "Internet English"); the Finnish have a designated word. The word is “pilkunnussija,”
Pilkunnussija's more lengthy dictionary definitions are actually pretty funny:
Noun (Vulgar, pejorative)- A person with exceptional and unnecessary attention to detail. Noun- A person who believes it is their destiny to stamp out all spelling and punctuation mistakes at the cost of popularity, self-esteem and mental well-being.
When you think about it, it's probably something we could use in the English language, especially for the more zealous of grammar correcting Internet users. We all have that one friend whose purpose in life is to correct grammar. Our proposed term in English might be to call them Daniels.
A tittle is a mark of punctuation used in the English language over letters like “i” and “j” in lowercase form. A tittle can also include marks like the tilde (~) and the umlaut, which is just two dots, though this can depend on whom you ask, as some debate on this topic.
Accent marks aren’t included in the definition of tittle, but not all letters with accents are without tittles as well, such as the ogonek (seen with letters like this one: Äaut;...). These are probably rare to many of our readers because they're symbols used mostly in non-Romance languages (languages other than ones such as Portuguese, English, Spanish, Italian, Latin, and French).
Some letters can use both ogoneks and tittles, but never in the English language, as well as most Romance languages. Other odd names for symbols: -Interrobang: ?! -Guillemet: > -Pilcrow: ¶ -Solidus: / -Circumflex: -Caret: ^