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What does the CSV Duplicate Remover do?
Mailing lists, exports and merged spreadsheets often contain the same record more than once. This CSV cleaner finds duplicate rows and removes them, keeping the first occurrence. You decide what counts as a duplicate: an identical row, or rows that share the same value in specific columns such as an email address — optionally ignoring capital letters and extra spaces.
How to use the CSV Duplicate Remover
- Upload a .csv file or paste CSV text. The delimiter (comma, semicolon or tab) is detected automatically.
- Tell the tool whether the first row contains column headings.
- Choose the column or columns to check. Leave all unticked to compare entire rows.
- Review the original, duplicate and cleaned row counts, then download the cleaned CSV.
Your privacy
Your CSV is read and processed in your browser using the File API. It is never uploaded, so customer lists and other sensitive data stay on your device.
Frequently asked questions
Which row is kept when duplicates are found?
The first occurrence is kept and later copies are removed. The order of the remaining rows is unchanged.
Can I remove duplicates based on one column only?
Yes. Tick just that column — for example “Email” — and any row whose email has already appeared will be removed, even if other columns differ.
How large a CSV file can I clean?
Files of several hundred thousand rows usually work well on a modern computer. The limit depends on your device’s memory, since nothing is processed on a server.
Will it change my data or formatting?
Kept rows are written back unchanged. The downloaded file uses the same delimiter as your original, with values quoted only where needed.