How to remove duplicate rows
- Paste CSV or open a file. The input box shows how many rows and columns were found.
- Choose Whole rows to remove exact repeats, or Key columns and tick the columns that identify a record, for example email, or first name plus last name.
- Decide how strict the comparison is and which copy to keep. The result and the list of removed rows update as you change options.
- Copy or download the deduplicated file.
Tips
- Mailing lists usually need the email column only, with case ignored: addresses are not case-sensitive in practice.
- To find near-duplicates caused by stray spaces or non-breaking spaces, run the file through the CSV cleaner first.
- The removed-rows table shows each removed row with the row number of the copy that was kept, so you can check the decision before downloading.
Frequently asked questions
Which copy is kept?
With Keep first, the earliest row of each group stays where it was and later copies are removed. With Keep last, the latest copy stays in its own position and the earlier ones are removed. All other rows keep their order.
How do the case and whitespace options work?
Values are compared after lowercasing and after trimming and collapsing runs of spaces, so "Ann Lee" typed with two spaces matches "ann lee". The kept row is written exactly as it appears in the file; only the comparison is relaxed.
What about rows with an empty key?
By default a blank key is a value like any other, so two rows with a blank email are duplicates of each other. Tick "Keep rows with a blank key" to leave all of them in place.