CSV Deduplicator
Paste or upload CSV below and click Deduplicate to remove repeated rows. Match by the entire row or a specific column, and optionally ignore case and trim whitespace. Everything happens locally in your browser — your data never leaves your device.
Read the guide: How to remove duplicate rows from CSVInput
Output
Processed locally in your browser — nothing is uploaded.
How the CSV Deduplicator works
- Your CSV is parsed in a background Web Worker using RFC 4180 rules, so quoted commas and newlines are handled correctly.
- A key is built for each row — either the joined values of every column or just the column you select.
- Keys are optionally trimmed and lowercased based on your settings.
- The first row for each key is kept; later duplicates are dropped, and the clean CSV is re-emitted with proper quoting.
Examples
Simple duplicates
name,city Ada,London Alan,Manchester Ada,London Grace,New York
Duplicates by one column
id,name 1,Ada 2,Alan 1,Grace
Useful tips
- Use Match by and pick an ID column to dedupe on a key field while keeping all other columns.
- Turn on Ignore case to treat London and london as the same value.
Frequently asked questions
Is my CSV sent to a server?+
No. All deduplication happens entirely in your browser. Nothing is uploaded or stored.
How are duplicates detected?+
By default two rows are duplicates when every column matches. You can narrow this to a single column with the Match by dropdown, so rows sharing that key are treated as duplicates even if other fields differ.
Does it handle quoted fields with commas?+
Yes. The CSV is parsed following standard RFC 4180 quoting rules, so commas and newlines inside quoted values are handled correctly and don't create false matches.
Which duplicate is kept?+
The first occurrence of each row is kept. All later duplicates are removed.
