Deduplicator
Remove duplicate rows from your data based on a specific column.
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Remove Duplicate Rows from CSV, Excel, and ODS
Duplicates are one of the most common data quality issues. They inflate counts, skew analytics, and cause double-counting in reports. DataScrub finds and removes duplicates based on any column or combination of columns, so you can trust your numbers.
Whether you are cleaning a mailing list before a campaign or deduplicating a merged dataset, this tool handles it entirely in your browser. No data leaves your machine.
How to Remove Duplicates
- Upload your CSV, Excel, or ODS file.
- Select the column or columns to check for duplicates.
- Choose whether to keep the first or last occurrence.
- Preview the rows that will be removed.
- Download your clean, deduplicated file.
Common Causes of Duplicate Data
Duplicates rarely appear on purpose. They creep in through everyday workflows and are surprisingly hard to spot by eye.
- Multiple data entry points — the same customer record created in two systems.
- Copy-paste errors — rows accidentally duplicated when assembling a spreadsheet.
- Merged datasets — combining exports from different sources without deduplication.
- API retries — a failed request that gets retried, creating a second record.
- Imported data without unique keys — no way for the system to catch duplicates on import.
Tips for Better Deduplication
- Check multiple columns for compound duplicates — first name plus last name is more reliable than either alone.
- Keep the first occurrence unless you have a reason to prefer the last (for example, if the most recent entry is more accurate).
- Profile your data first to estimate the scope of duplicates before removing them.
- After deduplicating, verify the row count matches your expectation before sharing the file.
Frequently Asked Questions
What counts as a duplicate?
A duplicate is any row where the values in your selected columns match another row exactly. If you check only the email column, two rows with the same email but different names are considered duplicates. If you check both email and name, both fields must match.
Can I check multiple columns?
Yes. Selecting multiple columns means all selected values must match for a row to be flagged as a duplicate. This is useful for compound keys like first name plus last name, or order number plus line item.
What happens to the removed rows?
The removed rows are excluded from the output file. You can preview exactly which rows will be removed before applying, so nothing is deleted unexpectedly. If you need a record of the duplicates, download the file before and after, or keep the browser tab open.
Is there a limit on file size?
Since all processing happens locally in your browser, the limit depends on your device memory. Most modern computers handle files up to 50 MB comfortably. Very large files may slow down the preview but the deduplication itself is fast.