Lite Tools

Duplicate Line Remover

Remove duplicate lines from text with smart options.

Options

Choose whether results are joined by newlines or commas

How to use

  1. Paste the text to deduplicate into the input box, one entry per line.
  2. Tick options as needed: ignore case, trim spaces, remove empty lines; the first occurrence's order is kept by default: uncheck "Keep original order" to sort alphabetically.
  3. Pick the output separator (newline or comma) and press "Remove duplicates".
  4. The stats show raw lines, unique lines and lines removed; copy the result from the output box in one click, or press "Clear" to reset everything.
  5. All processing runs locally in your browser: logs, lists and other sensitive text never leave your device.

FAQ

Which duplicate is kept?
In keep-order mode, only the first occurrence of each line survives and later duplicates are dropped; in sort mode the unique lines are deduplicated first and then sorted alphabetically, so no unique line is ever lost.
How does "Ignore case" compare lines?
When enabled, each line is lowercased for comparison, so "Apple" and "apple" count as the same line. The output keeps the original casing of the first occurrence: nothing is rewritten.
How are blank and whitespace-only lines handled?
With "Remove empty lines" checked, empty lines and lines containing only whitespace are dropped. If unchecked, blank lines participate in deduplication like any other line, so consecutive blanks collapse into one.
When is comma-separated output useful?
It is handy for pasting results straight into a spreadsheet, a SQL IN list or a single-line config. Note that if the lines themselves contain commas, you may need to quote or escape them afterwards.

How to use

  1. Paste text line by line

    Paste keyword lists, logs or email rosters into the box, one entry per line. No pre-cleaning is needed, because repeated lines are exactly what this tool finds.

  2. Tick the options you need

    Trim spaces and remove empty lines are on by default. Enable Ignore case so Apple and apple count as the same line when casing should not matter.

  3. Choose the output separator

    Output separator offers newline or comma. Newlines suit further line-by-line processing, while commas let you paste straight into a spreadsheet or a SQL IN list.

  4. Dedupe and check the stats

    Press Remove duplicates and the stats show raw lines, unique lines and lines removed. That makes it easy to confirm the cleaning matched your expectations.

  5. Copy the result or reset

    Use the Copy button above the output to grab the deduplicated text. Clear everything before the next batch so old lines cannot leak into it.

About this tool

This tool compares your text line by line and keeps only the first occurrence of each repeated line. The rest are dropped, and the stats report raw lines, unique lines and lines removed. Options cover case-insensitive matching, trimming leading and trailing spaces, deleting empty lines, and switching from original order to alphabetical sorting. Everything is computed locally in your browser, and nothing is sent to any server.

It suits keyword lists, subscriber emails, bulk URL lists, log lines and survey responses. Merge several sources, deduplicate once, then store the result. Lists too long for spreadsheet dedupe tools are handled just as easily. Case-insensitive matching quietly merges email addresses that differ only by capitalisation, which spreadsheet filters often miss.

How it works

The job is a single linear scan. A hash set remembers every line seen so far, and any later duplicate is skipped. Even tens of thousands of lines finish in an instant. Two preprocessing steps decide what counts as equal: trimming leading and trailing whitespace, and optionally folding case. That is how Apple and apple merge while a space hidden mid-line survives untouched. Keeping the first occurrence also preserves each survivor's original spelling for downstream checks. Nothing leaves the browser, so lists containing customer data stay on your machine.

The command line solved this long ago. sort -u sorts and deduplicates in one step. uniq only collapses adjacent repeats and demands sorted input, a subtlety that still trips people up. A graphical tool trades parameter memorisation for choices the shell makes awkward. Keeping the original order matters because log analysis and list cleaning depend on when a line first appeared, and sorting erases that information. Running both modes and comparing the outputs is also a simple way to check the cleaning logic.

When to use it

  1. Merging contact lists

    Subscribers arrive from forms, support tickets and offline signups with inconsistent capitalisation. Deduplicate with case folding on, check how many rows disappeared, and the mailing list is ready to send.

  2. Slimming log or crawl data

    Crawled URL lists and logs repeat heavily. Removing duplicates first shrinks the dataset before analysis, and keep-first-order mode preserves the earliest occurrence when sequence matters for debugging.

  3. Preparing database imports

    Tables with unique constraints reject an INSERT the moment a duplicate appears. Clean the ID or email column first, confirm the unique count matches expectations, then run the import with confidence.

Tips & tricks

  • Keep-order mode preserves each line's first occurrence. Sort mode deduplicates first and then sorts alphabetically. Neither ever loses a unique line.
  • With Ignore case enabled the output keeps the first occurrence's original casing, so nothing about the surviving lines is rewritten.
  • Be careful with comma output when lines contain commas themselves. Quote or escape them before pasting into a spreadsheet.

Things to watch

  • Case folding merges more than typos

    With Ignore case on, deliberate variants such as HTTP and http collapse into one line. Product codes differing only in case merge too. Turn the option off when casing itself carries meaning in your list.

  • Comma output needs care

    Switching the separator to commas only changes how results paste out. Lines that already contain commas will split into extra columns in a spreadsheet, so keep newlines or quote those rows first.

  • Whitespace counts as a difference

    Trimming plus empty-line removal means two lines differing only by a trailing space merge silently. If whitespace is meaningful data, disable those options, or the removed-lines stat will overstate the cleaning.

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