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Duplicate Line Remover

In-browser only Live dedupe Keep first or remove all
R remove ·C copy ·F full screen
12 lines
7 lines
11Lines processed
4Duplicates removed
7Unique lines
36%Reduction
Processed in your browser — nothing is uploaded.
Removed lines4 removed
Related tools All text tools

About this tool

Everything you need to clean duplicate lines

Two dedup modes, six comparison options, live statistics, and a removed-lines audit — all running client-side.

  • Two modes — keep first occurrence or remove every duplicate
  • Six matching options — case, trim, inner spacing, punctuation, blanks, sort
  • Live statistics — see exactly what was removed and the % reduction
  • Audit panel — every removed line with its original line number
  • Accepts paste, drag-and-drop, or .txt / .csv / .log / .tsv upload
  • Your text is processed locally in your browser
  • Nothing is ever uploaded to a server
  • Each run recomputes in memory on the page
  • Closing or refreshing the page erases everything
  • Clean mailing lists and keyword lists with repeated entries
  • Deduplicate log lines from server or application logs
  • Prepare CSV or TSV column values before import
  • Consolidate copy-pasted notes that contain repeated lines
  • Remove repeated survey responses or form submissions

How to use

Remove duplicate lines in four steps

  1. 1
    Paste or upload your text

    Type or paste text directly into the input box, or click Upload to load a .txt, .csv, .log, or .tsv file. You can also drag and drop a file onto the input area.

  2. 2
    Choose your deduplication mode

    Select "Keep first" to retain the first occurrence of each line and discard later repeats. Select "Remove all duplicates" to strip every instance of any line that appears more than once.

  3. 3
    Tune the comparison options

    Use the six option switches to control how lines are compared: ignore capitals, ignore leading/trailing spaces, collapse inner spacing, ignore punctuation, remove empty lines, or sort the result alphabetically.

  4. 4
    Copy or download the result

    The deduplicated output appears instantly in the Output box. Click Copy to copy to the clipboard, or Download to save as deduplicated-lines.txt. Click "Show removed lines" to see an audit of every line that was stripped.

Reference

Modes & options explained

Modes & options explained
Mode / OptionEffect
Keep firstKeeps the first occurrence of each line; all later repeats are removed.
Remove all duplicatesRemoves every instance of any line that appears more than once; only truly unique lines survive.
Ignore capitalsFolds case before comparing, so "Apple", "apple", and "APPLE" are treated as the same line.
Ignore leading/trailing spacesTrims whitespace from each end before comparing, so "hello " and "hello" are considered equal.
Ignore inner spacingCollapses multiple consecutive spaces inside the line to a single space before comparing.
Ignore punctuationStrips symbols and punctuation characters before comparing, so "hello!" and "hello?" match "hello".
Remove empty linesExcludes blank lines from the output and from the "Lines processed" count (default: on).
Sort A→ZSorts the deduplicated output alphabetically using locale-aware comparison (default: off — insertion order preserved).

Frequently asked questions

Is my text sent to a server?
No. All processing happens directly in your browser using JavaScript. Your text never leaves your device.
How does it decide which lines are duplicates?
By default, two lines are duplicates if their text is identical character-for-character. The option switches let you relax this — for example, enabling "Ignore capitals" makes "Apple" and "apple" match.
How large a file can I process?
The tool handles files up to 10 MB uploaded via the file picker. For pasted text, the practical limit is the amount of text your browser can handle in memory — typically tens of thousands of lines with no performance issues.
What is the difference between "Keep first" and "Remove all duplicates"?
"Keep first" keeps one copy of every line — the first time it appears — and removes all later repeats. "Remove all duplicates" is stricter: if a line appears more than once, every occurrence is removed, leaving only lines that were unique from the start.
What happens to blank lines?
With "Remove empty lines" on (the default), blank lines are excluded from the output entirely and do not count toward the processed total. Turn it off to treat blank lines like any other line — duplicate blanks will be deduplicated to a single blank.
Can I use this on a CSV file?
Yes. Upload a .csv file and the tool treats each row as a line of text. It does not parse CSV columns — it compares entire rows. This is ideal for finding exact-duplicate rows.
Does it support accented characters or emoji?
Yes — the tool is fully Unicode-aware. Emoji are treated as single characters and compared correctly. Note: the tool does not normalise Unicode, so a precomposed character (e.g. é as U+00E9) and the same character written as a base letter plus a combining accent are treated as distinct lines.