Remove Duplicate Lines from a List
Paste any line-based text — a list, an export, a set of email addresses — and this strips out repeated lines while keeping everything in its original order. The first time a line shows up, it stays; every later repeat of that same line gets dropped.
How does it decide what's a duplicate?
Each line gets trimmed of leading and trailing spaces, then compared exactly against every
line seen so far. If it's new, it's kept (in its trimmed form); if it's already appeared,
it's dropped. That means "Chicago" and " Chicago " count as the
same line, but "Chicago" and "chicago" don't — comparison is
case-sensitive.
Does it keep the original order?
Yes. Whatever order the unique lines first appeared in is the order they come out in. This tool never sorts or rearranges — for that, use the alphabetical sort tool instead, either before or after deduplicating.
What happens to blank lines?
Blank lines are treated as lines too, so multiple consecutive blank lines collapse down to one — the first blank line is kept, the rest are removed just like any other duplicate.
Why does it keep both "Email@site.com" and "email@site.com"?
Because comparison is case-sensitive by design — the tool has no way to know whether your data treats case as meaningful or not. If you're cleaning up something like an email list where case shouldn't matter, run your text through the lowercase converter first, then deduplicate. That guarantees anything that differs only in capitalization gets collapsed into one entry.
Is there a size limit?
No hard limit, but very large pastes (tens of thousands of lines) will naturally take a little longer to process than a short list, since it's all happening live in your browser as you type.
Other ways to deduplicate
If this is part of a bigger workflow rather than a one-off cleanup: spreadsheet apps have a
built-in "remove duplicates" feature under their Data menu, the Unix command line offers
sort -u file.txt or sort file.txt | uniq, SQL has
SELECT DISTINCT, and in Python list(dict.fromkeys(lines))
deduplicates a list while keeping the original order — the same behavior this tool gives
you without writing any code.
Related tools
- Duplicate Word Finder — find repeated words inside a single line, not repeated lines.
- Remove Line Breaks — collapse multi-line text into one paragraph.
- Sort Words Alphabetically — reorder lines A-to-Z.
- Find and Replace Text — swap patterns instead of removing duplicates.
- Whitespace Remover — strip extra spaces throughout a block of text.
Last reviewed: August 2026