Remove Duplicate Lines Tool
Clean up your text by removing duplicate lines instantly. Perfect for processing lists, data sets, and text documents.
About Our Duplicate Line Remover
Our free online tool helps you clean text documents by removing duplicate lines while preserving the original order (unless you choose to sort). Whether you're working with data sets, code, lists, or any text with repeated lines, this tool provides quick and accurate deduplication.
The duplicate line remover is particularly useful for:
- Cleaning up exported data from databases or spreadsheets
- Processing log files and removing repeated entries
- Preparing mailing lists by removing duplicate emails
- Cleaning up code files with repeated lines
- Processing survey responses or form submissions
- Analyzing word lists or vocabulary collections
Key Features
Case Sensitivity
Choose whether to treat "WORD", "Word", and "word" as the same line or different lines.
Whitespace Handling
Ignore differences in spaces and tabs between otherwise identical lines.
Blank Line Preservation
Maintain document structure by keeping blank lines when needed.
Sorting Options
Alphabetize your results after removing duplicates for better organization.
How to Use This Tool
- Paste your text into the input box above (one item per line works best)
- Select your processing options (case sensitivity, whitespace, etc.)
- Click "Remove Duplicates" to clean your text
- View the statistics showing how many duplicates were removed
- Use the "Copy to Clipboard" button to copy the cleaned text
- Use the "Clear Text" button to start fresh with new text
Technical Details
The tool processes text line by line, comparing each line to all previous lines to identify duplicates. Here's what happens behind the scenes:
- Line Processing: Each line is processed individually
- Normalization: Lines are normalized based on your settings (case folding, whitespace trimming)
- Comparison: Each normalized line is checked against previously seen lines
- Output: Unique lines are preserved in their original order (unless sorting is enabled)
- Statistics: Detailed counts are calculated and displayed
Frequently Asked Questions
Yes, the tool can process up to 100,000 lines of text (approximately 2MB). For extremely large files, we recommend processing in chunks.
With "Preserve blank lines" enabled, empty lines are kept in the output. When disabled, all blank lines are removed regardless of duplicates.
Yes, the tool always keeps the first occurrence of each unique line and removes subsequent duplicates.
No, the original formatting (capitalization, spacing) of kept lines is preserved unless you enable options to ignore case or whitespace.
When "Show duplicate counts" is enabled, the tool will display how many times each line appeared in the original text.