🧹 Duplicate Line Remover
Clean up your text files efficiently by removing duplicate lines. Perfect for data processing, code cleanup, and document organization with advanced options for case sensitivity, empty line handling, and occurrence preference.
How to Use This Duplicate Line Remover
How to Remove Duplicate Lines:
- Paste or type your text content in the input area
- Choose case sensitivity - check "Case Sensitive" for exact matching
- Select which occurrence to keep - first found or last found
- Choose how to handle empty lines - preserve all or treat as duplicates
- Optionally normalize whitespace to treat " text " and "text" as duplicates
- Click "Remove Duplicates" to process your text
- View statistics and download the cleaned text file
Pro Tips: Use case-insensitive mode for user-generated content, enable whitespace normalization for cleaner results, and choose "Keep Last" for files where newer entries should take precedence!
How It Works
The Algorithm Behind Duplicate Removal:
Our duplicate line remover uses an efficient hash-based algorithm for optimal performance. Here's how it works:
- Text Processing: Split input text into individual lines
- Normalization: Apply case and whitespace normalization based on your settings
- Hash-based Detection: Use Set data structure for O(n) time complexity duplicate detection
- Order Preservation: Maintain original line order while removing duplicates
- Occurrence Selection: Keep first or last occurrence based on preference
Example: Input with duplicates "Apple", "banana", "Apple", "Cherry":
- Case-sensitive: Keeps "Apple", "banana", "Cherry" (first Apple kept)
- Case-insensitive: Same result but would catch "APPLE" vs "apple"
- Keep Last: Would keep second "Apple" instead of first
- Result: Clean, deduplicated text with original formatting
When You Might Need This
- • Data cleaning and CSV file preprocessing for analysis
- • Code review and duplicate import removal from projects
- • Log file analysis and error deduplication for debugging
- • Database export cleaning for business intelligence
- • Software development code optimization and cleanup
Frequently Asked Questions
Does this tool preserve the original line order?
Yes! Our duplicate line remover maintains the original order of your text. You can choose to keep either the first or last occurrence of each duplicate line, ensuring your document structure remains intact.
Can I remove duplicates while ignoring case differences?
Absolutely! The tool offers both case-sensitive and case-insensitive duplicate detection. Choose case-insensitive to treat 'Hello' and 'hello' as duplicates, perfect for cleaning user-generated content.
What's the maximum text size I can process?
Our tool can handle large text files efficiently. For optimal performance, we recommend files under 10MB, but larger files are supported with processing time varying by size. All processing happens locally in your browser for privacy.