Which copy of a duplicate is kept?

The first one. Everything after it is dropped, so the original order of the list survives — unlike a sort-then-dedupe, which rearranges everything as a side effect.

Why are two lines that look identical not being merged?

Almost always trailing whitespace, or a difference in capitalisation. Turn on whitespace trimming and turn off case sensitivity, and they will collapse.

Can I get only the lines that appeared more than once?

Not here — this keeps one of each and drops the rest. Extracting just the repeats is a different job, and it is worth being explicit that this page does not do it.

Home›Text Tools› Remove duplicate linesBrowser

Remove duplicate lines from a list

Keeps the first occurrence of each line and drops the rest, with optional case-insensitive matching and whitespace trimming.

Case sensitive

Trim whitespace

Input

Output

1 lines in, 0 out.

How to use it

1Paste your list into the input box, one item per line.
2Decide whether matching should be case sensitive, and whether to trim whitespace first.
3The de-duplicated list renders live, with a count of how many lines went in and came out.

Frequently asked questions

Which copy of a duplicate is kept?: The first one. Everything after it is dropped, so the original order of the list survives — unlike a sort-then-dedupe, which rearranges everything as a side effect.
Why are two lines that look identical not being merged?: Almost always trailing whitespace, or a difference in capitalisation. Turn on whitespace trimming and turn off case sensitivity, and they will collapse.
Can I get only the lines that appeared more than once?: Not here — this keeps one of each and drops the rest. Extracting just the repeats is a different job, and it is worth being explicit that this page does not do it.