Duplicate Line Remover

Delete duplicate lines from any list while keeping the original order — in your browser.

How to use

  1. Paste your list in the input field — one item per line.
  2. Choose whether to ignore case or surrounding spaces, then click "Remove duplicates".
  3. Copy or download the cleaned list. The status line shows how many duplicates were removed.

About this tool

Duplicate entries creep into every list: e-mail addresses merged from two exports, keyword lists built over weeks, spreadsheet columns pasted from different sources, log lines, tag collections, inventories. This tool removes them in one click — paste the list, press the button, and every repeated line disappears while the first occurrence of each item stays exactly where it was. The original order is never touched, which matters when the list is ranked or chronological.

The algorithm is a single pass over the lines with a hash set: each line is checked against the set of lines already seen; if it is new it goes to the output and is registered, if it was seen before it is dropped and counted. This makes deduplication instant even for lists with tens of thousands of lines. Two options control what counts as "the same line": "Ignore case" treats "Maria" and "maria" as duplicates, and "Trim spaces before comparing" ignores invisible spaces at the ends of a line — the most common reason two visually identical lines survive a naive dedup. Either way, the line that appears in the output is the original, untouched text of the first occurrence.

After each run the status line reports exactly how many duplicate lines were removed, so you can sanity-check the result against what you expected. Everything runs 100% in your browser — nothing is uploaded, which makes the tool safe for customer e-mail lists and other data you would not paste into a random website otherwise. For a full cleanup, pair it with the List Sorter to alphabetize the result or the Text Cleaner to fix spacing first.

Frequently asked questions

Does it change the order of my list?

No. Each item stays in the position of its first occurrence; only the later repetitions are removed. The output is your list minus the duplicates, in the original order.

Which copy of a duplicate is kept?

The first one, with its original text intact. Even when "Ignore case" or the trim option makes two different-looking lines match, the output shows the line exactly as it first appeared.

Does "Ignore case" rewrite my text?

No. It only affects the comparison — lines are lowercased internally to decide whether they match, but the output keeps the original capitalization.

How large can the list be?

Large. The deduplication is a single in-memory pass, so lists with tens of thousands of lines are processed instantly on any modern device.

Does my list leave my browser?

No. The whole process runs in JavaScript on your device — nothing is transmitted or stored, so it is safe for e-mail lists and other sensitive data.

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