Remove Duplicate Lines
Strip repeated lines from a list, keeping the first of each.
Paste a list — emails, URLs, keywords, log lines — and this tool removes the repeated entries, keeping the first time each value appears and leaving the rest in their original order. A live stats bar shows how much duplication there is before you commit, and two options let you decide how strictly lines are matched. Everything is processed in your browser, so even a long or sensitive list never leaves your device.
How duplicates are matched
The tool works line by line: it keeps the first occurrence of a value and drops any later repeats, preserving the order of the lines that remain. Two checkboxes control what counts as a match. Trim Whitespace (on by default) ignores leading and trailing spaces, so apple and apple are treated as the same and the trimmed version is kept. Case Sensitive is off by default, which means Apple and apple are considered duplicates; tick it to treat different capitalisation as distinct entries. Blank and whitespace-only lines are always removed, whatever the settings.
Read the stats before you commit
Even before you press the button, the stats bar previews the outcome: Input Entries counts the non-empty lines you pasted, Unique Entries shows how many would survive, and Redundancy is the percentage that are duplicates, to one decimal place. Toggling Case Sensitive or Trim Whitespace updates these numbers instantly, so you can see exactly how much each option changes the result before cleaning anything.
Cleaning and copying
Remove Duplicates rewrites the box in place with the deduplicated list, and Copy Cleaned Data puts the result on your clipboard. Because it edits the same box rather than a separate output, the original list is replaced once you clean it — if you need the untouched version, copy it first or paste it again afterwards.
Frequently Asked Questions
Which copy of a duplicate does it keep?
The first occurrence. Later repeats are removed, and the order of the lines that remain is left exactly as it was in your input.
Is matching case-sensitive?
By default no — "Apple" and "apple" are treated as the same line. Tick the Case Sensitive box to keep entries that differ only in capitalisation as separate.
Does it remove blank lines as well?
Yes. Empty and whitespace-only lines are always dropped, regardless of the case and trim options, so the cleaned list has no gaps.
What does the Redundancy percentage mean?
It is the share of your input lines that were duplicates, shown to one decimal. For example, 100 lines reduced to 80 unique entries reports 20.0%.