Remove Duplicate Lines
Remove duplicate lines from any list and see how many were dropped. Free, instant, and case-sensitive aware.
About Remove Duplicate Lines
Duplicate lines sneak into almost any list that gets pasted between applications, whether it is a mailing list, product catalog, exported spreadsheet, or configuration file. Removing them by hand is slow and error-prone, especially when the list is long or the duplicates are scattered.
The tool keeps the first occurrence of each line in its original position and drops later repeats, so ordering is preserved. Case-sensitive mode treats 'Apple' and 'apple' as distinct when enabled, and the summary tells you exactly how many lines were removed. Lists of tens of thousands of lines are processed in memory without issue.
Marketers cleaning exported contact lists, developers tidying build outputs, and anyone merging notes from multiple sources benefit. Teachers and organizers use it to dedupe sign-up sheets and attendance lists in seconds.
How to Use
- Paste your list of lines.
- Toggle case-sensitive mode if your list needs it.
- Copy the deduplicated output.
Example
apple banana apple cherry banana apple banana cherry
The duplicate entries for apple and banana are removed, leaving each unique item exactly once while preserving original order.
FAQ
Does this preserve the original order?
Yes. The first occurrence of each line stays in its original position; only later duplicates are removed.
What does case-sensitive mode do?
When off, 'Apple' and 'apple' are treated as the same line. When on, they're kept as distinct entries.
Can this handle large lists?
Yes. The tool processes lists in memory and handles tens of thousands of lines without issue.
Does it remove lines that differ only in trailing spaces?
Trailing whitespace is trimmed before comparison by default, so lines that differ only in invisible trailing spaces are treated as duplicates and removed from the output.
What happens if every line is identical?
Only the first occurrence is kept, so a file of one hundred identical lines becomes a single line, and the removal count reflects the other ninety-nine that were dropped.