Copy some text of your choosing (from a web page, a local document, etc.) and paste it into the text area in the top half of the page. Then click "Uniquify" and see the uniquified text in the bottom half of the page.
Case-sensitive means that
this are treated as different
words for uniquification purposes.
Punctuation-sensitive means that
treated as different words for uniquification purposes.
You can also select to retain paragraph breaks only (output will look fairly similar to the input text), all line breaks (output tends to resemble free verse), or no breaks at all (output is one long unbroken stream of text.)