How are blank lines handled?

With 'Preserve blank lines' enabled, empty lines are kept in the output. When disabled, all blank lines are removed regardless of duplicates. This helps maintain document structure when needed.

Can I remove duplicates but keep one copy?

Yes, the tool always keeps the first occurrence of each unique line and removes subsequent duplicates. You can also enable 'Show duplicate counts' to see how many times each line appeared originally.

Remove Duplicate Lines Tool

Clean up your text by removing duplicate lines instantly. Perfect for processing lists, data sets, code files, and text documents. All processing happens in your browser for maximum privacy.

Paste your text with duplicate lines below:1 lines

Processing Options

Ignore case (treat 'Word' same as 'word')

Ignore whitespace differences

Preserve blank lines

Keep empty lines (no whitespace)

Output Options

Sort lines alphabetically

Show duplicate counts

Original Lines

Unique Lines

Duplicates Removed

Reduction

Clean Text (Duplicates Removed):

Example Input/Output:

Original Text:

apple
banana
APPLE
  Banana
apple
cherry

Processed (ignore case, preserve blanks):

apple
banana
cherry

With counts (ignore whitespace):

apple (3 occurrences)
banana (2 occurrences)
cherry

About Our Duplicate Line Remover

Our advanced online tool helps you clean text documents by intelligently removing duplicate lines while preserving the original order (unless sorting is enabled). Whether you're working with data sets, code, logs, lists, or any text with repeated content, this tool provides fast and accurate deduplication with multiple processing options.

Who Benefits From This Tool?

Developers

Clean repeated code blocks
Process log files
Deduplicate configuration files

Data Analysts

Clean CSV data exports
Prepare datasets for analysis
Process survey responses

Writers & Editors

Remove duplicate content
Clean up transcriptions
Process interview notes

Administrators

Deduplicate mailing lists
Clean inventory lists
Process form submissions

Advanced Processing Features

Smart Comparison

Flexible options to ignore case, whitespace, or both when identifying duplicates, giving you precise control over the deduplication process.

Blank Line Handling

Choose whether to preserve blank lines and empty lines to maintain document structure or remove them for compact output.

Duplicate Counting

Optionally display how many times each line appeared in the original text, helping you analyze duplication patterns.

Performance Optimized

Efficient algorithms process up to 100,000 lines in seconds, with real-time statistics about the cleaning process.

Step-by-Step Usage Guide

Input your text - Paste or type your content into the input box. The tool automatically processes the text as you type.
Configure options - Set your preferences for case sensitivity, whitespace handling, blank line preservation, and output sorting.
Review statistics - See real-time metrics about lines processed, duplicates found, and space savings.
Copy results - Use the one-click copy button to transfer your cleaned text to the clipboard.
Start fresh - Clear the form with a single click when you need to process new content.

Technical Implementation

The tool uses efficient algorithms to process text line by line:

Line-by-line processing - Each line is processed individually while maintaining order
Normalization - Lines are normalized based on your settings (case folding, whitespace trimming)
Hash-based comparison - Uses optimized data structures for fast duplicate detection
Memory efficient - Handles large files without browser performance issues
Real-time stats - Calculates and displays processing metrics as you type

Frequently Asked Questions

What's the difference between "Preserve blank lines" and "Keep empty lines"?

"Preserve blank lines" keeps lines that contain only whitespace (spaces, tabs), while "Keep empty lines" preserves only completely empty lines (no characters at all). You can enable both options to maintain all spacing in your document.

How does this tool handle very large files?

The tool is optimized to handle up to 100,000 lines efficiently. For extremely large files, we recommend processing in chunks. The browser-based processing ensures your data never leaves your computer, maintaining privacy and security.

Can I use this tool to deduplicate CSV or TSV data?

Yes, the tool works well with CSV/TSV data when you want to remove duplicate rows. For more advanced CSV processing (like deduplicating based on specific columns), you might need a specialized CSV tool, but for whole-line deduplication, this tool works perfectly.

Does the tool work with right-to-left languages?

Yes, the tool handles all Unicode text including right-to-left languages like Arabic and Hebrew. The deduplication respects the original text direction and character encoding.

Can I deduplicate lines while keeping the last occurrence instead of the first?

The current version always keeps the first occurrence of each unique line. If you need to keep the last occurrence, you could first reverse your line order (using our Text Reverser tool), process it, then reverse the result.