Remove Duplicate Lines
Clean up any list by deleting repeated lines — with optional case-insensitive matching, trimming, sorting and blank-line removal.
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Quick answer
This tool removes duplicate lines from a list while keeping the first occurrence of each. Paste your lines, and it instantly shows a cleaned version plus a count of how many duplicates were removed. Add options to ignore case, trim spaces, sort A–Z or drop blank lines. It all runs in your browser, so your list stays private.
When duplicate lines creep in
Repeated lines sneak into all sorts of lists. Exporting and merging email lists often creates duplicates, combining keyword research from several sources leaves overlap, and copy-pasting data from multiple pages piles up repeats. Duplicates inflate counts, skew analysis and waste time. This tool strips them out in one step, so what you are left with is a clean set of unique entries.
Matching options explained
Sometimes lines are not identical but should still count as the same. Case-insensitive matching treats Gmail and gmail as one entry, which is essential for emails and URLs. Trim whitespace ignores stray leading or trailing spaces that would otherwise make two visually identical lines look different to the computer. Combining both catches the maximum number of true duplicates while still preserving genuinely distinct lines.
Sorting and cleaning up
Turn on Sort outputto arrange the unique lines alphabetically — handy when you want a tidy, scannable list or plan to compare it against another. Remove empty lines clears out the blank rows that often separate pasted sections, giving you a compact result. Leave every option off and the tool simply removes exact duplicates while keeping your original order intact, then the Copy button hands the finished list straight back to you.
Frequently asked questions
How does it decide which lines are duplicates?+
The tool keeps the first time a line appears and removes every later line that matches it exactly. By default the match is exact, but you can turn on case-insensitive matching and whitespace trimming to treat near-identical lines as the same.
What does case-insensitive matching do?+
With it on, lines that differ only in capitalisation are treated as duplicates — so Apple, apple and APPLE collapse to a single entry. The first occurrence is kept with its original capitalisation.
What is the difference between trim and remove empty lines?+
Trim whitespace strips leading and trailing spaces and tabs from each line before comparing, so a line with a stray trailing space is seen as a duplicate of the clean one. Remove empty lines deletes blank lines entirely from the output.
Can I sort the results?+
Yes. Turn on Sort output and the remaining unique lines are ordered alphabetically (A to Z). Leave it off to keep the lines in their original order with duplicates removed.
Is my list uploaded anywhere?+
No. All processing happens in your browser with JavaScript. Nothing you paste is uploaded or stored, so it is safe for private lists such as emails, keywords or customer data.