Remove Duplicate Lines
This tool removes duplicate lines from a list while keeping the first occurrence of each in its original position. Comparison can ignore case and surrounding whitespace, and you can invert it to show only the lines that were duplicated.
Lines
Result
Your result will appear here.
Not sure where to start? Use Load example.
Results update automatically and are calculated on your device. Nothing you type is sent to a server.
Runs in your browser. Processing happens entirely in your browser. Nothing you enter is sent to Delimiter.live.
How to use the Remove Duplicate Lines
- Paste your list, one item per line.
- Choose whether you want the unique list, only the duplicated lines, or only the lines that appeared exactly once.
- Turn on case-insensitive matching if "Apple" and "apple" should count as the same item.
- Copy or download the cleaned list.
Example
Input
apple banana apple
Output
apple banana
Common use cases
- Cleaning a mailing list before an import so contacts are not messaged twice.
- De-duplicating a list of URLs, SKUs or keywords collected from several sources.
- Finding which entries in an export are repeated, using duplicates-only mode.
- Merging two lists by pasting them together and reducing to unique values.
Limitations and things to watch for
- Lines are compared as whole strings. Two lines that differ by a single character — including an invisible one such as a non-breaking space — are treated as different. Run the text cleaner first if your source has inconsistent whitespace.
- The original order is preserved rather than sorted; use the line sorter if you also want the list ordered.
Frequently asked questions
Does it keep the original order?
Yes. The first occurrence of each line stays exactly where it was, and later repeats are removed. Nothing is re-sorted.
Can I see which lines were duplicated instead of removing them?
Yes — choose "Show only lines that appeared more than once". That mode lists each repeated value once so you can review it.
Is the comparison case-sensitive?
By default yes, so "Apple" and "apple" are different lines. Tick the case-insensitive option to merge them.
Is my list uploaded anywhere?
No. De-duplication runs in your browser, which matters when the list contains customer emails or internal identifiers.