Case Converter
Sentence case, Title Case, camelCase, snake_case and the rest — in one click.
AP style leaves articles, short prepositions and conjunctions in lower case unless they start or end the title.
How it works
Most of these are one line of code. The one that is not is Title Case, and it is the one people get wrong.
Capitalising every word is not title case in any published style. AP, Chicago and the rest all keep articles (a, an, the), coordinating conjunctions (and, but, or, nor) and short prepositions in lower case — unless the word is first or last in the title, where it is always capitalised regardless. "The Man in the High Castle", not "The Man In The High Castle". That rule is implemented here, with the alternative available when you genuinely want every word raised.
Sentence case has its own subtlety: it must lower the rest of the sentence without destroying proper nouns, and no program can reliably tell "I met Mark" from "I left a mark". This lowercases and capitalises after sentence-ending punctuation, and leaves the standalone pronoun "I" alone. Anything else it will flatten, so check names afterwards.
The programmer cases — camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE — all work by breaking the input into words first, which means they convert correctly *between* each other rather than only from plain prose. Feed `getUserName` in and you get `get_user_name`, not `getusername`, because the split understands a lower-to-upper boundary is a word break. That is the part most converters get wrong, and it is the part you need when renaming things across two languages with different conventions.
Common questions
What is the difference between Title Case options?
AP style leaves articles, conjunctions and short prepositions in lower case except at the start or end of the title — that is what published style guides specify. The other option capitalises every word, which is what people often mean by 'title case' but no style guide endorses.
Will it break my proper nouns?
Sentence case will, in some cases. There is no reliable way to tell a name from an ordinary word without understanding the sentence, so names other than the pronoun 'I' get lowercased. Check afterwards.
Can it convert camelCase to snake_case?
Yes, and correctly. The splitter treats a lower-to-upper transition as a word boundary, so getUserName becomes get_user_name rather than getusername. Consecutive capitals are handled too: parseHTTPResponse becomes parse_http_response.
Is my text uploaded?
No. All of it happens in this page.