Duplicate Finder takes a pasted block of text — one item per line — and picks out every line that appears more than once, which is a common but tedious thing to check by eye in a spreadsheet export, an email list, or a survey's free-text responses. An optional case-sensitive matching toggle lets you decide whether “Apple” and “apple” should count as the same entry or as different ones.
It's built for a quick paste-in, click, and read-the-results workflow rather than requiring a spreadsheet formula or a script — useful for cleaning up mailing lists, checking for accidental repeats in a dataset, or verifying a list of unique codes really is unique before you rely on it.
How to Use Duplicate Finder
- Paste your list into the Input list box, one item per line.
- Toggle Case-sensitive matching on if "Apple" and "apple" should count as different entries; leave it off to treat them the same.
- Click Find Duplicates.
- Read the Results box: each repeated line is listed once with its total count (e.g. "apple: 3"); if nothing repeats it shows "No duplicates found."
- Click Copy results to copy the output to your clipboard.
Features
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Finds every repeated line in a pasted list
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Optional case-sensitive matching
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No file upload needed — just paste and go
