Text deduplication
Remove duplicate lines from a text file
Mailing lists, logs, and exported data fill up with repeated lines. The duplicate line remover removes them with case and whitespace options, and the text cleanup guide covers the surrounding cleanup steps.
Clean a list in four steps
The first occurrence is kept; later matches are removed.
Open the tool
Load the duplicate line remover.
Paste the text
Paste the list or open a text file locally.
Set the options
Choose case-sensitive or trimmed matching as needed.
Run and copy
The cleaned list appears with the number of removed lines.
How matching works
By default, exact line matches are removed and the first occurrence is kept. Case-insensitive and trimmed matching catch near-duplicates that differ only by formatting.
After deduplication, run the text through the whitespace cleaner to normalize spacing for the final result.
When deduplication misbehaves
- Lines that differ only by trailing spaces being treated as unique
- Case differences creating near-duplicates
- Removing lines that were intentionally repeated
Best practices
- Trim whitespace first for reliable matching
- Review the removed count before replacing a file
- For lists, pair with the list deduplicator for the same job on separated values
Frequently asked questions
Which occurrence is kept?
The first occurrence of each line is kept and later duplicates are removed.
Can I ignore case differences?
Yes. The case-insensitive option treats "Apple" and "apple" as duplicates.
Does it handle trailing spaces?
The trim option normalizes whitespace before matching, catching near-duplicates.
Is my text uploaded?
No. Everything runs locally in your browser.
Your text stays local
Deduplication runs in your browser. The text never leaves your device.
Open Duplicate Line Remover