Duplicate Line Remover
Remove repeated lines from a pasted list while preserving the order of the first occurrence. Optional trimming and case-insensitive comparison cover common cleanup needs.
Runs locally in your browser
1 duplicate line removed. Original order is preserved.
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What is the Duplicate Line Remover?
Remove repeated lines from a pasted list while preserving the order of the first occurrence. Optional trimming and case-insensitive comparison cover common cleanup needs.
How to use it
- 1Paste one item per line.
- 2Choose whether spaces and letter case affect matching.
- 3Copy the unique-line result.
How it works
Each line is normalized according to the selected options, then compared against a Set. Only the first occurrence of each comparison key is retained.
A repeated list
Apple, Banana, Apple on three lines becomes Apple, Banana in that order.
Limitations & notes
- Blank lines are treated as values, so one blank line can remain.
- Case-insensitive comparison follows browser locale casing, not linguistic equivalence.
Frequently asked questions
Does removing duplicate lines change the order of my list?
No. The tool walks through your lines from top to bottom and keeps the first time each line appears, dropping later repeats. A list of Banana, apple, Banana, Cherry comes out as Banana, apple, Cherry. If you also want the result alphabetized, run it through a sort afterwards; sorting first and deduplicating second gives the same unique set, just in a different order.
Why are lines that look identical not being removed?
Usually because of invisible differences. A trailing space, a tab, or a leading space makes "apple" and " apple " different strings. Turn on Trim each line before comparing to ignore spaces at both ends; the trimmed version is what appears in the output. Capitalization also counts by default, so "Apple" and "apple" both stay unless you enable Ignore case. Spaces inside a line are never collapsed, so "New York" with two spaces still differs from "New York".
When Ignore case is on, which spelling is kept?
The first one. If your list contains Paris, PARIS and paris in that order, only Paris survives, because the tool compares lowercase copies of each line but writes out the original text of the first match. If you need a specific spelling to win, move that line to the top before deduplicating, or convert the whole list to one case first with a case converter.
How can I count how many duplicates a list had?
The status line under the boxes reports how many lines were removed, for example "2 duplicate lines removed". That number is the original line count minus the unique line count, so it includes repeated blank lines too. To find how many unique entries you have, paste the result into a word or line counter. The total updates instantly as you edit the input or switch options, so you can compare the effect of trimming or case-insensitive matching.
Can I deduplicate a CSV or spreadsheet column with this?
Yes, as long as you paste one value per line. Copying a single column from Excel or Google Sheets gives exactly that. For whole CSV rows, the full row text is compared, so two rows count as duplicates only if every field matches character for character. The tool cannot match on one column while keeping others; use your spreadsheet's remove duplicates feature for that. Windows line endings are accepted and the output uses plain newlines.
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