Remove Duplicate Lines

What Does This Tool Do?

This tool removes duplicate lines from your text, keeping only unique lines. When duplicate lines are found, only the first occurrence is kept, and subsequent duplicates are removed. The original order of lines is preserved. This is useful for cleaning up lists, removing redundant data, or preparing text for further processing.

Common Use Cases

• Data Cleaning: Remove duplicate entries from lists or datasets
• Email Lists: Clean up email lists by removing duplicate addresses
• Log Files: Remove duplicate log entries for easier analysis
• URL Lists: Deduplicate lists of URLs or links
• Code: Remove duplicate import statements or configuration entries
• Research: Clean up lists of keywords, tags, or references

Features

• Instant duplicate removal as you type
• Preserves the order of first occurrences
• Case-sensitive comparison (treats "Hello" and "hello" as different)
• Preserves empty lines if they're unique
• One-click copy to clipboard
• 100% client-side - your text stays private
• No registration or download required
• Works on all devices and browsers

How Duplicate Detection Works

• Exact Match: Lines must match exactly, including spaces and punctuation
• Case Sensitive: "Apple" and "apple" are treated as different lines
• Whitespace Matters: Leading/trailing spaces make lines different
• First Wins: The first occurrence of each line is kept

Tips for Best Results

• Trim whitespace first: If you want "apple " and "apple" to be treated as duplicates, remove extra spaces first
• Case normalization: Convert all text to lowercase first if you want case-insensitive deduplication
• Sort first: Sorting lines before deduplication can help you verify results

Frequently Asked Questions