How are nested arrays handled?

Array items are flattened using their index as part of the column name.

Can I change the separator?

Yes, set any separator like '.' or '_' for flattened keys.

What if rows have different fields?

Missing fields are left blank in the resulting CSV row.

JSON to CSV Flattener

Deep-flatten nested JSON objects and arrays into CSV.

Works Offline

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No Login

No API

Key separator

JSON input

Flattened CSV

id,name,address.city,address.zip,tags.0,tags.1
1,Ada,London,E1,admin,eng
2,Grace,NYC,10001,ops,

About the JSON to CSV Flattener

Convert an array of nested JSON objects into a flat CSV file, deep-flattening nested objects and arrays with a customizable key separator so every value gets its own column.

Examples

Nested object

[{"a":{"b":1}}]

Output

a.b
1

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Frequently asked questions

Version 1.0.0 · Updated 2026-08-09 · Runs entirely in your browser