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Join CSV Tables

Join two CSV tables by unique, non-empty keys with inner, left or full joins.

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01
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02
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03
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CSV key join tool online

Combine two tables using an explicit unique key. Empty or repeated join keys are rejected; choose inner, left or full behavior deliberately.

How to use it

Enter Left CSV or select Try example. Provide Right CSV in the second editor. Review Key column, Join type. Select Run tool and inspect the result before copying or downloading.

Options and example settings

Option	Choices / value	Example default
Key column	Enter a value	id
Join type	left; inner; full	left

Worked examples

Combine two tables using an explicit unique key.

Worked example — Join CSV Tables

Settings: Key column: id; Join type: left

Input:

id,name
001,Anna
002,Ben

SECOND INPUT:
id,city
001,Tirana
003,Rome

Output:

left.id,left.name,right.id,right.city
001,Anna,001,Tirana
002,Ben,,

The example output has 3 lines. Compare its order, separators and whitespace with the input before copying the result.

Choose the right tool

Join matches rows by a selected key. It differs from Merge CSV Files, which appends rows. Confirm key uniqueness and choose the join type before interpreting unmatched records.

Limitations and common mistakes

Empty or repeated join keys are rejected; choose inner, left or full behavior deliberately.

Frequently asked questions

How can I combine two CSV tables by unique, non-empty keys with inner, left or full joins online?

Enter Left CSV or select Try example. Provide Right CSV in the second editor. Review Key column, Join type. Select Run tool and inspect the result before copying or downloading.

Where is my input processed?

The bundled tool processes input in your browser. It does not upload tool input to a conversion service. Other site plugins, analytics, advertising and browser extensions may have separate behavior.