CSVFormat Portal
Home/Tools/Remove duplicate rows from CSV

Remove duplicate rows from CSV

Remove duplicate rows in one click. Choose which columns define a duplicate, so you can keep several contacts at the same company while dropping true repeats. Everything runs in your browser.

No uploadNo sign-upExtract duplicates too
Process your CSV Runs on your device
Drop a CSV here
or click to choose · Shift_JIS / UTF-8 detected
Load a CSV to see its columns.

How to use

  1. Drop a CSV file or paste the table.
  2. Tick the columns that define a duplicate (all columns when none is ticked).
  3. Press Run, check the result, then download the CSV.

What this tool does not do

Matching is exact — “Acme Inc.” and “Acme, Inc.” count as different. Normalize the values first if you need fuzzy matches.

FAQ

Is the comparison exact?
Yes — values in the selected columns must match exactly. Turn on “ignore surrounding spaces” or “ignore case” to normalize before comparing.
Can I export only the removed rows?
Yes. After running, use “Download removed rows” to save just the duplicates that were dropped.
Which row is kept?
The first occurrence by default. Switch to “keep the last row” to keep the later duplicate instead.
How large a file can it handle?
It runs within browser memory — hundreds of thousands of rows on a normal PC. The preview shows the first 60 rows only.
Is my data uploaded?
No. Reading, comparing and exporting all happen in your browser; nothing is sent to a server.

Related tools

Compare two filesAdded / removed / changedMerge CSV filesStack files into oneCSV ⇄ JSONConvert both ways