This tool walks your text line by line and keeps only the first time each unique line appears, discarding every later repeat while preserving the original order of what remains. It's handy for cleaning up exported lists, log files, CSV-like data, or any paste job where the same line got duplicated by accident. With the whitespace option on, lines that differ only by leading or trailing spaces are still treated as duplicates.
The first occurrence is kept and every later repeat of that exact line is removed, so the overall line order in your original text is preserved.
Yes — "Apple" and "apple" are treated as different lines, since capitalization can be meaningful in things like code or identifiers.
When it's on, lines are compared after trimming spaces from both ends, so " hello" and "hello" count as the same line for duplicate detection — but the version kept in the output is exactly as it appeared originally.
Paste a list with one item per line and every repeat is dropped. The first time a line appears it stays; later copies go. The order of what's left is the order you started with, so the list doesn't get shuffled behind your back.
People reach for it with email lists, keyword lists, log files, URL lists and anything exported from a database where the same value turns up more than once. There's a trim option, on by default, which ignores spaces at the start and end of a line when deciding whether two lines match, so duplicates that differ only by an invisible trailing space still get caught.
Lines that differ in capitalization, like Apple and apple, are different lines. If you need those treated as the same, lowercase the list first.
apple banana apple cherry banana
apple banana cherry
Blank lines count as lines too, so only the first empty line survives. If you were relying on blank lines to separate paragraphs, you'll need to put them back.