Remove Duplicate Lines
Strip duplicate lines from a list in one click — privately, right in your browser.
How it works
Paste a list — emails, URLs, keywords, log lines — and every line that repeats an earlier one is dropped, keeping the first occurrence and its original order. Two switches control what counts as a duplicate: comparing case-insensitively (so "Foo" and "foo" match) and trimming each line's edges before comparing (so trailing spaces don't hide a duplicate). The result updates live as you type, and the count of removed lines is shown above the output so you can see at a glance how much repetition was in your list.
Everything runs locally in your browser tab — nothing is uploaded to a server, which matters when the list you're cleaning is a customer email export or an internal contact sheet.
FAQ
Does this keep the first or the last occurrence of a duplicate line?
The first occurrence is kept and every later repeat is removed, so the order of your remaining lines matches the order they first appeared in.
Will "Email@Example.com" and "email@example.com" count as duplicates?
Only if you enable "Case-insensitive compare" — by default comparison is case-sensitive, so those two lines are treated as different.
What does "Trim each line before comparing" do to the output?
It only affects which lines are considered equal — trailing or leading spaces are ignored for comparison purposes, but the surviving line is kept exactly as you typed it, spaces included.
Is there a limit on how many lines I can paste?
No hard limit — it's plain JavaScript running in your tab, so very large pastes (tens of thousands of lines) work, though extremely large inputs may feel slightly less snappy since there's no server to offload the work to.
Is my text uploaded anywhere?
No — deduplication happens entirely in your browser. Nothing is sent to a server, and refreshing the page clears everything.