Remove Duplicate Lines
Remove duplicate lines from a list with case-sensitivity, trim, and empty-line controls. Runs entirely in your browser.
0 lines
Paste any list and get back only the unique lines. Choose whether comparisons are case-sensitive, whether leading and trailing whitespace counts, and whether to keep the first or last occurrence of each duplicate.
Duplicate-line cleanup comes up constantly: merged CSV exports, combined email lists, log files, word lists for password audits, and any time two data sources overlap. Doing it manually is tedious and scales badly beyond a few dozen rows. This tool splits the input on line breaks, compares entries against a configurable key, and rebuilds the output preserving the original order of the survivors.
The four switches cover the edge cases that make naive dedupe fail. Case-sensitivity decides whether 'Apple' and 'apple' are the same row. Trim whitespace ignores stray spaces and tabs picked up from copy-paste. Ignore empty lines leaves blank separators untouched in the output instead of collapsing them. Keep-first vs keep-last controls which copy survives when duplicates appear, which matters when later entries contain the fresher data. Everything runs locally in your browser, so pasting customer emails or internal IDs never leaves the page.
- 1
Paste your list
Drop one entry per line into the input box. Any number of lines works, from a few dozen to tens of thousands.
- 2
Pick comparison rules
Toggle case-sensitivity, whitespace trimming, empty-line handling, and whether to keep the first or last copy of each duplicate.
- 3
Remove and copy
Click Remove duplicates to see the deduplicated output along with a count of how many rows were collapsed. Copy the result with one click.
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Deduplicate word lists
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Is my input uploaded anywhere?
No. Deduplication runs in your browser with plain JavaScript. The text never leaves your machine.
Does it preserve the original order?
Yes. Lines appear in the same order they were pasted, minus the duplicates you chose to remove. Keep-first keeps the earliest copy; keep-last keeps the latest.
How do empty lines behave?
When 'Ignore empty lines' is on, blank rows pass through to the output untouched and never count as duplicates. Turn it off to treat blanks like any other line and collapse consecutive empties.
What counts as whitespace when trimming?
Standard JavaScript trim: spaces, tabs, and newline-adjacent whitespace at the start and end of each line. Interior whitespace inside a line is kept as-is.
Is there a line limit?
No hard limit. The tool handles hundreds of thousands of lines in most browsers. Very large inputs may feel slower on low-end devices.