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Remove Duplicate Lines
Remove duplicate lines from text.
Overview
- Compares each line of text and removes exact duplicate lines while preserving the order of first occurrence.
- Useful when you want to create a unique list from a list containing duplicate lines, such as email addresses, logs, or tags.
- You can toggle whether blank lines are treated as duplicates.
Usage
- Enter the text you want to remove duplicates from into the text area.
- Choose whether blank lines should be treated as duplicates.
- Click the "Remove Duplicates" button to see the deduplicated result along with the line counts before and after.
Example
Input
a b a c b
Output
a b c
Use Cases
- Creating a unique list from a list of email addresses or URLs by removing duplicates
- Removing duplicate error message lines from a log file to see the list of distinct types
- Cleaning up a list of tags or categories exported from a CSV or text file
FAQ
Is the comparison case-sensitive?
Yes. Only lines that match exactly are treated as duplicates, so lines that differ only in case are treated as distinct lines.
Does the order of lines change?
No. The order of first occurrence is preserved, and only lines that appear again later are removed.
How are blank lines handled?
When "Treat blank lines as duplicates" is enabled, blank lines are treated as duplicates too, so any blank line after the first is removed. When disabled, all blank lines are kept.
Notes
- Only exactly matching lines are treated as duplicates. Lines that differ in case or whitespace are treated as distinct.
- The order of lines does not change. The position of first occurrence is preserved, and only later duplicate occurrences are removed.
- Processing very large text may make browser processing slow.
Related Tools
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Count the characters, words, and lines in your text.
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