Data Deduplicator
Remove duplicate rows from CSV data.
Processed locally in your browser. Your data is never uploaded.
- Deduplicate by the whole row, or by a single key column like email or ID.
- Keeps the first occurrence and preserves row order.
- Runs in your browser — safe for contact lists and other personal data.
Why this is private
- Processed locally in your browser. Your data is never uploaded.
- Open your browser's DevTools → Network tab while using this tool — you won't see a request carrying your input, because it never leaves your device.
- Nothing you enter is uploaded to a server or shared with us — the processing happens entirely on your device.
Overview
Removes duplicate rows from CSV data, either by comparing entire rows or just one chosen column (e.g. deduplicate by email address).
How to use it
- 1Paste CSV data with a header row.
- 2Choose whether to compare entire rows or one specific column.
- 3Review the deduplicated table.
Frequently asked questions
What people use it for
Clean a contact or subscriber listRemove repeated email addresses before importing into an email platform.
Merge two exportsConcatenate two CSVs, then dedupe by a unique ID column.
Remove exact duplicate transactionsCompare full rows to strip accidental re-exports.
Prepare a mailing list for a supplierDeliver a deduplicated file to avoid paying for repeat records.
Related tools
All data toolsReady to use Data Deduplicator?
Data Deduplicator