Case converter
Switch text between upper, lower, title, and sentence case.
Runs entirely in your browser — your text is never uploaded.
The four cases and when each one is right
UPPERCASE is for short labels and constants. Used on a full sentence it reads as shouting and measurably slows people down, because readers recognise words partly by their outline and uppercase flattens every word into the same rectangle.
lowercase is useful for normalising data before comparison — email addresses, tags, slugs, and lookup keys are conventionally lowercased so that two spellings of the same value match.
Title Case is for headings and titles. Sentence case capitalises only the first word and anything already capitalised, and it is what most style guides now prefer for interface copy and headlines because it is easier to scan.
How title case is applied here
Title case is not simply capitalising every word. Short joining words — a, an, and, as, at, but, by, for, in, of, on, or, the, to, up, via, with — stay lowercase unless they are the first or last word of the title, which is the convention shared by most English style guides.
Sentence case works by lowercasing the input and then capitalising the first letter of each sentence, detected after a period, question mark, or exclamation mark. Because the input is lowercased first, proper nouns and acronyms will need fixing by hand — an unavoidable trade-off, since no tool can reliably tell a name from an ordinary word without understanding the text.
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