Does this tool keep the first or last occurrence of a duplicate line?

The first occurrence is always kept; every later repeat of the same line is removed. The original order of the remaining lines is preserved exactly.

Does it sort or reorder my list?

No. Only exact repeats are removed — the surviving lines stay in their original order. If you want a sorted list, sort it separately after deduplicating.

What does the 'Case-sensitive' toggle do?

When on, 'Apple' and 'apple' are treated as different lines and both are kept. When off, they're treated as duplicates of each other, and only the first one encountered is kept — with its original casing preserved in the output.

What does the 'Trim whitespace' toggle do?

When on, leading and trailing spaces/tabs are ignored when comparing lines (and stripped from the output), so 'apple' and ' apple ' count as duplicates. When off, whitespace differences make lines count as distinct, and the original spacing is kept untouched.

Does this remove duplicate words within a single line, or only whole duplicate lines?

Only whole duplicate lines are removed — each line is compared to other lines in full. It does not look inside a line for repeated words or phrases.

Are blank lines treated as duplicates of each other?

Yes — multiple blank lines are treated like any other repeated line. If your text has three blank lines in a row, only the first is kept (unless you disable both toggles in a way that makes them distinct, which isn't possible for truly empty lines).

Is there a limit to how much text I can paste in?

There's no hard-coded limit, but extremely large inputs (hundreds of thousands of lines) may process slightly slower since everything runs synchronously in your browser.

Is my text uploaded to a server?

No. All deduplication happens locally in your browser using JavaScript. No network request is made, and nothing you paste is stored or transmitted.

Remove Duplicate Lines — Free Online Deduplication Tool

Our Remove Duplicate Lines tool cleans up any pasted text by removing repeated lines while keeping the first occurrence of each and preserving the original order — no re-sorting, no reshuffling. Toggle case-sensitive matching on or off, and choose whether to trim leading/trailing whitespace before comparing lines, so near-identical entries (like 'Apple' and 'apple ') can be treated as duplicates or kept distinct depending on what you need. A live count shows exactly how many lines were removed. Nothing is uploaded — everything runs instantly in your browser.

Quick Answer

A Remove Duplicate Lines tool cleans up a pasted list or block of text by deleting repeated lines, keeping only the first occurrence of each and preserving the original order. Toggle case-sensitive matching and whitespace trimming to control what counts as a duplicate. Free, and everything runs instantly in your browser — nothing is uploaded.

Your text

Deduplicated output

Your deduplicated text will appear here

How to Use the Remove Duplicate Lines

1
Paste or type your list or block of text into the input box.
2
Toggle 'Case-sensitive' off if 'Apple' and 'apple' should be treated as the same line.
3
Toggle 'Trim whitespace' off if you want to keep lines with only leading/trailing space differences as distinct.
4
The deduplicated output updates instantly, along with a count of how many lines were removed.
5
Click 'Copy' to copy the cleaned-up result.

Why Use Remove Duplicate Lines?

Duplicate lines creep into lists constantly — exported CSV columns, merged email lists, log files, copy-pasted URLs, keyword lists, or notes assembled from multiple sources all tend to accumulate repeated entries. Manually scanning a long list to find and delete duplicates is slow and error-prone, especially when duplicates aren't adjacent to each other. This tool handles it instantly: paste your text and every line after the first occurrence of a duplicate is removed, while the original order of the remaining lines is preserved exactly as it was — nothing gets reordered or alphabetized unless you do that yourself. Two options control what counts as a 'duplicate': case-sensitive matching (so 'Apple' and 'apple' are either treated as identical or kept distinct) and whitespace trimming (so a line with a trailing space isn't treated as different from an otherwise identical line). Everything runs locally in your browser using a single pass over the text, so even large pasted lists are deduplicated instantly with no upload or processing delay.

Frequently Asked Questions

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