How to use Remove duplicate CSV rows
- Load the example to check the expected input shape, or select your file. Keep a separate copy of the original.
- Review the options and rules below. Run the tool, then compare representative values, row counts and headers.
- Copy the output or download a new file. Input changes clear the previous result so you cannot download stale output.
Rules and limitations
Key columns are 1-based: use 1 or 1,3, or leave blank to compare complete rows. Empty keys also match. Case and leading zeros matter. Ignoring surrounding whitespace affects matching only. Last means file order, not the latest date; values from discarded rows are not combined.
Worked example
Use the English example button above. Identifiers such as 0012 are strings; they should not silently become 12. For conversion, compare record counts before and after. For cleaning, filtering, comparison and lookup, check the operation-specific summary.
The example has four data rows, including two rows for 0012. With key column 1, either retention mode produces three rows. First keeps Alex in Sales; last keeps Alex in Planning. The last mode outputs 0024, 0036, then 0012 because retained rows keep their source order.
Troubleshooting
If columns shift, check the delimiter and quote fields containing delimiters or newlines. If characters look wrong, select the encoding before loading the original file again. CSV has no stored cell types; spreadsheet software may infer numbers and dates when opening it.
Does my file leave my device?
The tool processes selected files and pasted input in browser memory. It does not upload the file or its name. Hosting providers may process page-request metadata such as IP address and requested URL. See the privacy notice.