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Remove Duplicate Lines

Deduplicate text lines instantly. Handles case sensitivity, whitespace trimming, and alphabetical sorting. Processes huge lists in your browser.

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Original
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Unique
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deduplicated
Paste lines above to remove duplicates

What is Remove Duplicate Lines?

The Remove Duplicate Lines tool scans your text line by line and eliminates all repeated entries, leaving only unique lines. This is essential when working with large data lists, log files, CSV exports, email lists, keyword lists, or any text where duplicates creep in. You can control whether comparison is case-sensitive (so 'Apple' and 'apple' are treated as the same or different), trim leading and trailing whitespace from each line before comparing, and optionally sort the results alphabetically. All processing happens instantly in your browser — even lists with thousands of lines are deduplicated in milliseconds. No data is sent to any server.

How to Use Remove Duplicate Lines

  1. 1

    Paste your text

    Paste or type your list of lines into the input area. Each line is treated as one entry.

  2. 2

    Configure options

    Toggle case-sensitive matching, whitespace trimming, and alphabetical sorting based on your needs.

  3. 3

    Review the stats

    The stat cards show original line count, unique lines, and how many duplicates were removed.

  4. 4

    Copy the result

    Click Copy to copy the deduplicated text to your clipboard.

Features

  • Instant duplicate line removal
  • Case-sensitive or case-insensitive comparison
  • Whitespace trimming before comparison
  • Optional alphabetical sorting of results
  • Shows original, unique, and removed counts
  • Handles thousands of lines instantly
  • One-click copy to clipboard

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Frequently Asked Questions

How does case-sensitive matching work?+
When case-sensitive is on, "Apple" and "apple" are treated as different lines and both are kept. When off, they are treated as the same and only the first occurrence is kept.
What does trim whitespace do?+
It removes leading and trailing spaces and tabs from each line before comparing. So " hello " and "hello" would be treated as duplicates. The output uses the trimmed version.
Does the tool preserve the original order?+
Yes, unless you enable the Sort A-Z option. Without sorting, the first occurrence of each unique line appears in its original position, with subsequent duplicates removed.
How many lines can it handle?+
There is no hard limit. The tool runs in your browser and uses a hash set for O(1) lookups, so it handles 10,000+ lines comfortably. Very large datasets (100K+ lines) depend on your device memory.
Can I use it to deduplicate email lists?+
Yes, it works perfectly for email lists. Paste one email per line, enable case-insensitive matching (since emails are case-insensitive), and the tool will remove all duplicate addresses.
Does it remove empty lines?+
Empty lines are treated like any other line — if there are multiple empty lines, only the first one is kept. If you want to remove all empty lines, you can copy the output and use a text editor to strip them.