Don's Tools · Text & Writing · Remove Duplicate Lines

Remove duplicate lines

Clean a list by removing repeated lines, right in your browser. Nothing is uploaded.

Keep
Private by design: your list is processed in your browser and is never uploaded. Duplicate detection compares whole lines; turn on Ignore case or Trim to match lines that differ only by capitals or spaces.
Remove Duplicate Lines is a free tool that removes repeated lines from a list entirely in your browser, with nothing uploaded. You can ignore case, trim spaces on each line, drop blank lines, keep either the first or last occurrence of each line, and optionally sort the result, then copy or download it.

Frequently asked questions

Is my list uploaded anywhere?

No. The lines are processed entirely in your browser and are never sent to a server.

How are duplicates decided?

Two lines are duplicates when they match exactly. Turn on Ignore case to treat capitals as the same, and Trim each line to ignore leading and trailing spaces.

Does it keep the order of my list?

Yes, the original order is kept unless you turn on Sort result. With Keep First it keeps the first time each line appears; with Keep Last it keeps the last.

Can it also remove blank lines?

Yes. Turn on Remove blank lines to drop empty lines as well as duplicates.

What is the difference between Keep First and Keep Last?

If the same line appears more than once, Keep First leaves the earliest copy in place and removes later ones, while Keep Last keeps the final copy.

Is there a size limit?

No fixed limit, but very large lists are handled in your browser and may be slower on an older device.