Remove Duplicate Lines

The tool reads your text line by line and keeps track of which lines it has already seen. When it encounters a line that matches a previous one, it removes the duplicate. The first occurrence of each line is always preserved, and the original order of unique lines is maintained.

By default the comparison is case-sensitive, meaning "Hello" and "hello" are treated as different lines. You can toggle case-insensitive mode to treat them as duplicates. In case-insensitive mode, the first occurrence's original casing is preserved in the output.

By default, lines must match exactly including leading and trailing whitespace. You can enable a trim option that strips whitespace from both ends before comparison, so " hello " and "hello" would be treated as duplicates. Internal whitespace differences are always detected.

Yes — this tool is perfect for cleaning up lists of any kind including email addresses, URLs, product SKUs, IP addresses, or log entries. Paste your list with one item per line and the tool instantly removes all duplicates while maintaining the original order.

Blank lines are treated like any other line. If your text has multiple blank lines, only the first one is kept and the rest are removed as duplicates. If you want to remove all blank lines entirely, you can combine this with the Whitespace Remover tool.