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What Is the Duplicate Line Remover?

The duplicate line remover is a free online text tool that instantly removes repeated lines from any block of text. Paste a list of email addresses, log entries, keywords, URLs, or any line-separated data and the tool outputs only unique lines. It is commonly used to clean up exported data, deduplicate word lists, filter log files, and remove repeated rows before importing into a spreadsheet or database.

Unlike simple sort-and-dedup scripts, this tool gives you fine-grained control: choose whether matching is case-sensitive, whether to trim whitespace before comparing, whether to keep the original order or sort the output, and whether to keep the first or last occurrence of each duplicate.

How to Use the Duplicate Line Remover

1. Paste your text into the left input area.
2. Configure options: case sensitivity, whitespace trimming, order, and which occurrence to keep.
3. The right panel updates instantly with all duplicate lines removed.
4. The green bar at the bottom shows how many duplicates were removed.
5. Click Copy to copy the deduplicated output to your clipboard.

Features

• Removes duplicate lines instantly as you type
• Case-sensitive or case-insensitive comparison
• Optional whitespace trimming before comparing
• Keep original order or sort output alphabetically
• Keep first or last occurrence of duplicate lines
• Shows count of original lines, unique lines, and removed duplicates
• Copy output to clipboard in one click
• Runs entirely in your browser — no data sent to servers

FAQ

How does the duplicate line remover work?

The tool splits your input on newlines, tracks which lines it has already seen, and outputs only the first (or last) occurrence of each unique line. Processing happens entirely in your browser — no data is sent to a server.

What is the difference between case-sensitive and case-insensitive matching?

With case-sensitive matching (the default), "Apple" and "apple" are treated as different lines. With case-insensitive matching enabled, they are treated as duplicates and only one is kept.

What does "Keep original order" mean?

When enabled, the output preserves the order lines appeared in the input — only duplicates are removed. When disabled, the output is sorted alphabetically.

Can I remove duplicate lines from a large file?

Yes. The tool runs in your browser and can handle large text inputs. For very large files (millions of lines), performance depends on your device but there is no server-side size limit.