Duplicate Line Remover

Paste a list and instantly remove all duplicate lines while preserving the original order. Supports case-insensitive matching and whitespace trimming — free.

What Does This Tool Do?

The Duplicate Line Remover scans your text line by line and keeps only the first occurrence of each unique line, removing every subsequent duplicate. The original order of unique lines is preserved.

Options Explained

• Case sensitive — when checked, “Apple” and “apple” are treated as different lines. When unchecked, they are treated as identical and only one is kept.
• Trim whitespace — strips leading and trailing spaces before comparing, so ” apple ” and “apple” are treated as the same.
• Keep empty lines — by default empty lines are removed; check this to preserve them.

Common Use Cases

• Deduplicating email lists or CSV exports
• Cleaning up keyword lists from multiple sources
• Removing repeated log entries
• Normalizing data before importing into a database

Frequently Asked Questions

Does it remove duplicates that are not adjacent?

Yes. The tool detects all duplicate lines regardless of their position in the text, not just consecutive repeats.

What is the maximum input size?

The tool works entirely in memory within your browser — it can handle tens of thousands of lines with no performance issues.