About CSV Deduplicate by Columns
Inspect headers, select one or more duplicate-key columns, control trimming and case matching, and keep the first matching row.
CSV Deduplicate lets you inspect the parsed columns and select the exact combination that defines equality. It keeps the first matching row and reports how many later rows were removed.
How to use it
- Paste or load a CSV and analyze its columns.
- Select every column that defines a duplicate record.
- Remove duplicates, verify the count, and download the result.
Common use cases
- Keep one row per customer, email, or external identifier.
- Remove repeated transactions using a composite key.
- Deduplicate exports without comparing unrelated descriptive columns.
Worked example
Keep the first row for each unique combination of customer_id and region.
Limitations and responsible use
- Exact key matching does not detect spelling differences, reordered names, or fuzzy duplicates.
- Choosing an incomplete key can delete legitimate distinct records.
- The first matching row wins; values from duplicate rows are not merged.
Frequently asked questions
Can I match using more than one column?
Yes. Select every column that belongs to the composite duplicate key.
Which duplicate row is retained?
The first row in source order is kept and later rows with the same selected key are removed.