What if key values have different cases?

Toggle case-insensitive matching to join regardless of case.

CSV Joiner

Perform SQL-style JOINs on two CSV files using a common key column. Fast, private, and secure browser-based tool with no sign

Your files never leave your device. Processed locally. 100% private.

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Complete your task perfectly in just three straightforward steps.

Upload the left and right CSV files to join.

Select key columns from each file and choose join type: INNER, LEFT, RIGHT, or FULL OUTER.

Download the joined CSV.

Everything you need to know about the CSV Joiner.

What join types are supported?

INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN — same as SQL.

Can I join on multiple columns?

Yes — add multiple key column pairs for composite key joins.

Is my file uploaded?

No. Everything runs locally in your browser.

File size limit?

Process files up to the browser memory limit.

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