CSV Column Duplicate Checker
Check for duplicate values within a specific key column (e.g. email, user ID, SKU).
How It Works & Processing Standards
Check for duplicate values within a specific key column (e.g. email, user ID, SKU).
Your input data is never sent to any server and is securely processed on your device.
Current Limits
- Desktop max file size: 50MB
- Mobile max file size: 20MB
CSV Column Duplicate Checker is a 100% free, browser-based online utility. All calculations and file conversions run locally inside your browser (Local-First) without sending data to remote servers, keeping your documents and inputs strictly private.
How to Use CSV Column Duplicate Checker
- 1Paste CSVEnter CSV table data.
- 2Select Key ColumnChoose the column that should contain unique values.
- 3View CollisionsInspect duplicate values and their corresponding row entries.
Examples
Duplicate Email Check
Input: id,email,plan
1,alice@example.com,free
2,bob@example.com,pro
3,alice@example.com,enterprise
Result: Duplicate in [email]: "alice@example.com" found in rows 1 and 3
Common Use Cases
- Verifying primary key uniqueness before relational database imports
- Finding duplicate customer accounts sharing the same email address
- Checking product catalogs for conflicting SKU numbers
Frequently Asked Questions (FAQ)
Can I deduplicate based on this column?
Yes, you can choose to keep only the first row matching each key value.