Convert tools

JSON to CSV converter — fields, nesting and Excel

Convert JSON objects to CSV locally. Select columns, flatten nested objects, choose delimiters and download UTF-8 CSV with optional BOM for Excel.

Convert in your browser · No sign-up

Up to 10 MB · Files are not uploaded

How to use

  1. Paste JSON or select a local file.
  2. Choose delimiter and flattening, then convert. Select fields and convert again to narrow the output.
  3. Check the preview and download CSV. UTF-8 with BOM helps Excel detect Japanese text.

Example

JSON: [{"id":"001","address":{"city":"東京"}}]
CSV:
id,address.city
001,東京

Details and limitations

Conversion data stays in this browser tab and is cleared on reload.

Limits: 10 MB input, 50,000 records, 2,000 columns and one million expanded JSON cells. Processing runs in a Web Worker.

Nested objects become dotted columns; arrays stay JSON strings. Literal dots and backslashes in keys are escaped. Null and missing values become empty cells.

Excel protection prefixes formula-like cells with an apostrophe. This changes values; disable it for faithful data interchange.