CaseKit

CaseKit is a free set of online text tools. Change text to UPPERCASE, lowercase, Sentence case, Title Case (APA, MLA, Chicago and AP rules), camelCase, snake_case and more. It also has a word and character counter, Find & Replace, Remove Line Breaks, Remove Extra Spaces, Sort & Remove Duplicate Lines, Add Line Numbers, a Slug Generator, a Fancy Text Generator and Reverse / Upside Down Text.

Everything runs in your browser, so your text is never uploaded. No sign-up, works on phones, and available in English, Spanish, Portuguese and German.