Duplicate Line Remover
Find, remove, extract, or highlight duplicate lines from plain text with optional case-sensitive matching.
Run tool
Duplicate Line Remover is a practical text utility designed to clean, filter, and inspect repetitive line-based lists. When working with server logs, inventory spreadsheets, email contact lists, or code snippets, duplicate entries often clutter datasets and distort record counts. This tool processes your text line by line to remove redundant lines, isolate repeating entries, or mark duplicate occurrences directly within your content.
You can configure how lines are evaluated. By default, the tool performs a case-insensitive check by converting lines to lowercase before comparing, while leaving trailing and leading spaces intact. Enabling case-sensitive evaluation preserves exact letter casing distinctions during matching. You can also retain the first recorded occurrence of each duplicate entry or select different modes. Extract mode gathers a single representative line for every recurring pattern, while highlight mode tags duplicate entries with an indicator prefix so you can review repeated items before deleting them.
Instructions
- Paste or type your multi-line content into the input text area.
- Select your preferred mode: remove duplicates, extract recurring lines, or highlight repeated lines.
- Toggle case sensitivity if letter casing should distinguish otherwise identical lines.
- Choose whether to keep the first occurrence of repeated items when removing duplicates.
- Run the tool to review the updated text in the output panel.
Examples
- Removing duplicates from a list containing 'apple', 'banana', 'Apple', and 'cherry' without case sensitivity produces 'apple', 'banana', and 'cherry'.
- Extracting duplicates from an email list where 'contact@example.com' appears three times returns a single 'contact@example.com' line.
- Highlighting repeated items in a server event log prefixes every subsequent occurrence of an error message with '>> ' for visual auditing.
FAQ
Does the tool automatically trim spaces around lines?
No. Line comparisons evaluate the full line content between newline characters. Lines with differing leading or trailing spaces are treated as distinct.
How does case sensitivity affect duplicate detection?
By default, the tool compares lines in lowercase, treating 'Sample' and 'sample' as duplicates. Enabling case sensitivity treats them as separate unique entries.
What happens if I run the tool with an empty text box?
After you click Run, the output panel shows an empty result because no duplicate lines exist.
How does highlight mode display duplicate entries?
In highlight mode, original unique lines remain unchanged, while lines identified as duplicate occurrences are prefixed with >>.