Duplicate Line Remover
Remove repeated lines using exact, case-insensitive, or outer-whitespace matching while keeping the first line unchanged.
Try a small example
Try a small example
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Example input
Ada Sam Ada
Expected output
Ada Sam
By default, removes exact duplicate lines and keeps the first occurrence unchanged. Other modes can ignore case, outer whitespace, or both.
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Quick answer
Choose how to compare lines: exact text, ignore letter case, ignore leading/trailing whitespace, or both. The first matching line stays exactly as written.
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How to use it
Paste text and choose how lines should match: exact, ignoring letter case, ignoring leading/trailing whitespace, or ignoring both. The first matching line stays unchanged; only later matches are removed. In whitespace-trim modes, blank and whitespace-only lines count as the same. Internal spaces are never changed, and line endings plus a final newline are preserved.
Limits
Case-insensitive matching uses the browser’s locale-aware lowercase mapping. Trimming is only for comparison; it does not remove spaces from the kept line. In trim modes, blank and whitespace-only lines match.
Frequently asked questions
When are lines considered duplicates?
Choose exact text, ignore letter case, ignore leading/trailing whitespace, or ignore both. The first matching line stays as written; only later copies are removed. Case-insensitive comparison follows the browser’s locale.
What happens to blank lines and line endings?
Exact mode treats a blank line and a whitespace-only line as different. In trim modes they match. Existing line-break types and a final newline are preserved.
Further guidance
Sources and references
These references document the cited standard or browser API; they do not validate the tool’s output.