How to Remove Duplicate Lines From a List

Copy a list from three different places and you'll almost certainly end up with repeats. Duplicate lines clutter keyword lists, bloat mailing lists and make logs harder to read. Removing them takes seconds once you know the details that matter.

Business charts and data on a laptop

What "duplicate" means

Two lines are duplicates when their text matches. But "matches" has options:

Case sensitive: "Apple" and "apple" are different lines.
Case insensitive: they count as the same.
Whitespace: "apple" and "apple " (with a trailing space) look identical but aren't — unless you trim spaces first.

Choosing the right combination is the difference between a clean list and one that still has near-duplicates.

Keep the first occurrence

The standard approach keeps the first time each line appears and removes later repeats, preserving the original order. This matters when the order carries meaning, such as a ranked list or chronological log.

How to remove duplicate lines

Paste your list into the Remove Duplicate Lines tool, one item per line.
Choose whether matching is case sensitive, and whether to trim spaces at the start and end of each line.
Decide whether to keep blank lines.
Copy or download the cleaned list. The tool shows how many lines went in, came out and were removed.

Everything runs in your browser, so lists containing private data — emails, customer names — are never uploaded.

Handy uses

Email and contact lists — avoid sending the same message twice.
SEO keyword lists merged from several tools.
Log files and exports with repeated entries.
Shopping, reading or to-do lists combined from several people.
Code and config files with duplicated lines.

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Sorting as well

Duplicates in a jumbled list are harder to spot by eye. Sorting first groups identical lines together, and the Sort Lines tool can also remove duplicates in the same step, though it changes the order. If you need to keep the original order, use the duplicate remover instead.

Common mistakes

Forgetting about trailing spaces, which make identical-looking lines different.
Leaving case sensitivity on when you want "Paris" and "paris" merged.
Removing blank lines by accident. Keep them if they separate sections.

FAQ

Will it remove duplicate words within a line? No — it works line by line. Put one item per line first.

Is there a limit on list size? Not a fixed one; it runs in your browser, so very large lists are limited only by your device's memory.

Can I undo it? Your original text stays in the input box, so you can change the options and try again.

Try it now

Open the free Remove Duplicate Lines tool.