A QUICK WALKTHROUGH
How to use this tool
- Load the CSV and choose its delimiter and header setting.
- Enter key column positions, such as 1,2, or leave blank for whole-row comparison.
- Choose first or last retention, then check the removed and retained counts.
How it works
Composite keys are compared as tuples of field strings. This avoids accidental collisions caused by joining fields with a delimiter that may already exist in their values. Matching is exact: whitespace, case and leading zeros remain significant. The original field values are preserved in retained rows.
A practical example
Start with
id,name 1,Ada 2,Sam 1,Ada
What to expect
Whole-row deduplication retains two data records and removes one.
Important considerations
Two records can share an ID while carrying different addresses. Whole-row comparison retains both; keying only on ID discards one according to the first/last setting. Make that choice deliberately.
5 MiB per input · 50,000 records · 200 columns. Input remains in page memory until you reset or leave. Copy and download actions are initiated by you. No tool input is sent to a processing service.
One more useful detail
Are column positions zero-based?
No. Position 1 means the first column shown in the table.