Text & String
Remove Duplicate Lines
Remove duplicate lines from pasted text and keep the first occurrence.
Results appear here.
What the result means
The result is your paste with repeated lines taken out, plus a count of lines that were dropped. The first time a line is seen it stays, and later copies are removed, so the order of what remains matches the original. Blank lines follow that same first-wins rule unless you remove blank lines, in which case every blank line is dropped. Trim and ignore case change the key used for comparison. Ignore case does not rewrite spelling. Trim also trims the line that is kept. Two lines that still differ after those options both stay. This is not a spreadsheet dedupe, and it does not join wrapped lines back together.
Related tools
Questions
Is matching case sensitive?
By default, yes, matching is case sensitive, so A and a are different lines. Tick ignore case to treat those as the same key. The line you keep is still the first original line, not a lowercased copy.
Is order kept?
Yes. The first time a line is seen, it stays where it was, and later copies are removed. The result is not sorted. A line that never repeats is unchanged in position relative to the other kept lines.
Do trim and ignore case rewrite the kept lines?
Ignore case changes the comparison key only, so spelling stays as it first appeared. Trim changes the key and also trims the line that is written back. Neither option reorders the lines.