Duplicate Line Remover
TextRemove duplicate lines from text while preserving order. Case-sensitive or case-insensitive mode. Shows count of duplicates removed.
About Duplicate Line Remover
This duplicate line remover deduplicates text line by line in your browser while preserving first-appearance order. It supports case-sensitive and case-insensitive modes. The algorithm leverages ES6 Set O(1) lookup, efficiently handling tens of thousands of lines without sorting. Upon completion it reports the removed duplicate count.
How to Use
- Open the Duplicate Line Remover tool page
- Enter or paste your data into the input area
- View the real-time results and use the copy button to get the output
Use Cases
- Log deduplication — Keep only unique entries from repeated log lines, reducing noise during log analysis.
- Data export cleanup — Remove duplicate rows from CSV or TSV data, preserving the first occurrence of each record.
- Code snippet cleanup — Clean up duplicate import statements or config lines in code to keep it tidy.
- Word list dedup — Deduplicate keyword lists or stop-word lists to ensure each entry appears only once.
- ID list dedup — Remove duplicates from user ID or order number lists to generate a unique identifier set.
FAQ
Does deduplication preserve the original order?
Yes. The tool preserves the order of first appearance for each line; subsequent duplicates are removed without reordering.
What is the difference between case-sensitive and insensitive?
In sensitive mode Foo and foo are distinct lines both kept; insensitive mode normalizes to lowercase, keeping only the first one.
How many lines can it handle?
Using ES6 Set O(1) lookup, tens of thousands of lines are deduplicated in milliseconds, suitable for large logs and data files.
Are empty lines treated as duplicates?
By default, multiple empty lines are deduplicated to one. To remove all empty lines, use the Empty Line Remover tool.
Is my data secure?
Yes. All deduplication runs locally in the browser with no network requests, safe for sensitive text.
Comments
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