Last updated October 12, 2026 · Report an error
Long lists — email addresses, keywords, URLs, product SKUs — often end up with accidental duplicate entries after merging multiple sources. Finding and removing them by hand is tedious and error-prone.
This tool removes duplicate lines automatically, keeping the first occurrence of each unique line and preserving the original order.
How it works
Paste your list, one item per line, and choose whether matching should be case-sensitive. The tool removes every line after its first occurrence and returns the cleaned list.
- Enter text (one item per line).
- Enter case sensitive.
- Click Calculate to see your results.
Examples
Deduplicating a keyword list
A list with "apple", "banana", "apple", "cherry" becomes "apple", "banana", "cherry" — the second "apple" is removed.
Who should use it
- Cleaning up email or contact lists merged from multiple sources.
- Deduplicating keyword or URL lists before further processing.
Industry applications
- Marketing and email list management
- SEO and content research
Advantages
- Instant deduplication that preserves original line order.
- Optional case-insensitive matching for messier lists.
Limitations
- Compares lines exactly, so trailing whitespace differences aren't normalized automatically.
Common mistakes to avoid
- Forgetting to check case sensitivity settings when a list mixes inconsistent capitalization.
- Assuming trailing whitespace differences won't affect matching, when they currently do.
Best practices
- Run a whitespace cleanup first if your list has inconsistent spacing, then deduplicate for the cleanest result.
Tips
- Use the Whitespace Remover tool first if your list has inconsistent spacing, since this tool compares lines exactly as entered.
Frequently asked questions
Yes, with no signup and no limit on how many times you use it.
The first occurrence of each unique line is kept, and every later repeat of that exact line is removed — this preserves your original ordering.
With case sensitivity on, "Apple" and "apple" are treated as different lines; with it off, they're treated as duplicates of each other.
No — lines are compared exactly as entered, so "apple" and "apple " (with a trailing space) are currently treated as different lines.