Remove Duplicate Lines

Remove duplicate lines from text instantly. Keep unique lines with case-sensitive or case-insensitive matching. Free online tool.

Last updated: June 1, 2026

Case sensitiveTrim whitespace

Input

Result (unique lines)

What is Remove Duplicate Lines?

A duplicate line remover scans through text line by line and removes repeated entries, leaving only unique lines. This is essential when working with lists, log files, data exports, email lists, or any text where duplicates have crept in through copy-pasting, data merging, or system exports. The tool can preserve the original order of first-appearing lines or sort the results alphabetically. It handles large files with thousands of lines efficiently, making it useful for data cleaning tasks that would be tedious to do manually.

How It Works

The tool splits your input on newline characters, creating an array of individual lines. It then uses a set-based approach to track which lines have already been seen. As it processes each line sequentially, duplicates are identified and removed while preserving the first occurrence in its original position. You can choose case-sensitive or case-insensitive comparison, and optionally trim whitespace before comparing. The tool reports how many duplicates were removed so you can verify the cleanup met expectations.

Common Use Cases

•Cleaning up email lists by removing duplicate addresses from merged mailing lists
•Deduplicating log file entries to identify unique error messages and events
•Cleaning data exports from databases or APIs that contain repeated records
•Removing duplicate URLs from crawl lists, sitemaps, or link collections
•Cleaning up word lists, keyword lists, or tag lists for content management
•Preparing unique line items from combined inventory or product lists