How to use the remove duplicate lines tool
- Paste or drop your list. One item per line works by default. For comma-separated data change “Input is separated by”.
- Choose what to do with duplicates. Remove duplicates keeps the first copy of each item. “Keep only duplicated items” lists what repeats, and “Keep only items that appear once” strips everything that has a twin.
- Decide how strict matching is. Turn on “Ignore case” so Apple and apple count as the same item, and keep trimming on so trailing spaces do not hide duplicates.
- Copy or download the cleaned list. The counters show how many lines went in, how many came out and how many were removed.
Common uses
- Clean a mailing list or CRM export before importing it
- Deduplicate keyword, URL, SKU or username lists
- Find the entries that appear more than once in a log or spreadsheet column
- Merge two lists (paste both) and keep only one copy of each line
Frequently asked questions
How do I remove duplicate lines from a list?
Paste your list into the input box. With “Remove duplicates (keep first)” selected, the output instantly shows each line once, in its original order.
Is the duplicate check case-sensitive?
By default yes, so Apple and apple are different. Tick “Ignore case when matching duplicates” to treat them as the same; the first spelling is kept.
Can I find only the lines that are duplicated?
Yes. Choose “Keep only duplicated items” to list each repeated line once, or “Keep only items that appear once” to drop every repeated line entirely.
Will it keep my original order?
Yes, unless you choose a sort option. The first occurrence of every line stays where it was.
Why are lines that look identical not removed?
They probably differ by invisible whitespace or letter case. Keep “Trim whitespace” on and try “Ignore case”.
Is there a size limit?
Only your device’s memory. Lists with hundreds of thousands of lines work in most browsers, and nothing is uploaded.
More tools: Email Extractor · Compare Lists · Remove Duplicates · Sort Lines · List Converter