Flatten Nested JSON to CSV

Turn nested JSON (objects inside objects, arrays of records) into a flat CSV with one column per field. Free, in your browser.

Quick answer: Convert JSON, CSV, Parquet and Excel – one file or a whole folder.

Related: JSON, CSV, Parquet and Excel Converter · JSON to CSV Converter · CSV to JSON Converter · CSV to Parquet Converter · CSV Guides and Free CSV Tools

How to use the Flatten Nested JSON to CSV

Convert JSON, CSV, Parquet and Excel – one file or a whole folder.

The Format Converter moves data between JSON, CSV, Parquet and Excel without code or an install. It reads your file in the browser, flattens nested JSON into columns, keeps or guesses column types, and writes the format you choose. Use it to open API data in Excel, load a spreadsheet into an app, shrink a big CSV into Parquet, or look inside a Parquet file. Nothing is uploaded, so it is safe for customer and business data.

  1. Pick From and To
  2. Drop or paste your data
  3. Convert and download

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Example

Input: {"user":{"name":"Ana","city":"Pune"}}

Output: user.name,user.city → Ana,Pune

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Who uses Data Utility

Frequently asked questions · Data format benchmark

Frequently asked questions

How are nested fields named?

With dots, such as user.address.city, so every value gets its own column.

Can I edit nested JSON as a table?

Yes. The JSON Table Editor shows nested arrays as a table and exports JSON again.

How big can a file be?

It depends on your device. A few hundred MB usually works.

Which conversions does the Format Converter support?

Any direction between JSON, CSV, Parquet and Excel (.xlsx), for one file or a whole folder. Nested JSON is flattened into columns such as address.city. For Excel, the first sheet is read; old .xls files are not supported.

Why did my number or date change after converting?

Types are detected from the values. Turn off "Detect types" to keep everything as text, which also keeps leading zeros in IDs and phone numbers.

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