Remove Duplicate Lines
Remove repeated lines with case and whitespace options. Keep the first occurrence in its original order and copy the cleaned list.
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Remove Duplicate Lines
The first occurrence is always kept in its original position; there is no sorting mode. Trimming changes both comparison keys and output lines, while internal spaces stay unchanged. Empty lines are discarded by default; Keep one empty line retains only the first empty comparison key. With trimming off, a spaces-only line is not empty. Case-insensitive comparison lowercases keys with the selected page language explicitly, so changing the browser’s default locale does not change that page’s comparison rules. It does not apply Unicode normalization or full Unicode case folding: composed é and e plus a combining accent remain distinct. Use case-sensitive mode for identifiers when case matters; deduplicating email text does not verify addresses or delivery.
A a B A → A B
Processing takes place locally in your browser.