CSV Deduplicate Tool
Remove duplicate rows from any CSV file instantly by matching whole rows or chosen columns. Free, no signup, works in your browser.
Everything runs inside your browser — your file is never uploaded to a server.
About this tool
Upload or paste a CSV file and this tool scans every row to find and remove duplicates, either by comparing entire rows or by matching values in specific columns you choose, such as an email or ID field. It keeps the first occurrence of each unique value and discards later repeats, showing you exactly how many duplicate rows were removed before you download the cleaned file. This is especially useful for cleaning up mailing lists, merged datasets, or exports that accumulated repeated entries over time. All parsing and comparison happens locally as JavaScript in your browser, so contact lists and other sensitive data are never sent anywhere. Download the deduplicated CSV or copy it straight to your clipboard once processing finishes.
How to use this tool
1. Add your CSV
Paste CSV text or choose a .csv file from your device.
2. Choose comparison columns
Select whole rows or specific key columns to detect duplicates.
3. Remove duplicates
Click deduplicate to instantly clean the dataset.
4. Download the result
Save the cleaned CSV or copy it to your clipboard.
Why use this tool
Duplicate rows sneak into datasets from repeated imports, merged sources, or manual data entry, skewing reports and wasting outreach effort. This tool finds and removes them instantly, whether comparing entire rows or specific key columns, saving you from manually scanning spreadsheets or writing formulas.
Tips & best practices
- Choose a unique key column like email or ID for the most accurate duplicate detection.
- Trim extra spaces in your data beforehand, since ' John ' and 'John' may otherwise count as different values.
- Review the summary count after deduplicating to confirm the results match your expectations.
Common use cases
- Cleaning a mailing list before sending an email campaign.
- Removing repeated entries after merging customer data from multiple sources.
- Deduplicating a product catalog exported from multiple supplier feeds.
- Cleaning survey responses that were accidentally submitted more than once.
- Preparing a clean contact list before importing it into a CRM.
Frequently asked questions
Can I deduplicate based on just one column instead of the whole row?
Yes, you can choose one or more key columns, like email or ID, so duplicates are detected by those values alone.
Which occurrence of a duplicate is kept?
The first occurrence in the file is kept by default, and later duplicate rows are removed.
Will it tell me how many duplicates were removed?
Yes, a summary shows the number of duplicate rows found and removed before you download the result.
Does capitalization affect duplicate detection?
Comparison is case-sensitive by default, so 'Email' and 'email' are treated as different unless normalized first.
Is my CSV file uploaded to a server?
No, deduplication happens entirely in your browser and your file never leaves your device.
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