Mr. Encoder

JSON ↔ CSV Converter

Convert JSON arrays to CSV (with flattened nested fields) and CSV files back to JSON.

How to use

  1. Paste a JSON array of objects on the left, or CSV data on the right.
  2. Pick a delimiter and, for CSV input, whether the first row is a header.
  3. Click JSON → CSV or CSV → JSON, check the preview table and copy or download the result.

Frequently asked questions

How are nested JSON objects converted to CSV?

Nested objects are flattened into dot-separated column names, so {"address": {"city": "London"}} becomes an address.city column. Arrays are written into a single cell as JSON text.

What if objects have different keys?

The header is the union of all keys found in every object, in the order they first appear. Missing values are left empty.

Which delimiter should I use for Excel?

It depends on your system region. Excel in locales that use a decimal comma (such as Turkish or German) expects a semicolon (;), while English locales expect a comma. The downloaded CSV includes a UTF-8 BOM so special characters display correctly in Excel.

What does "Convert numbers and booleans" do?

When enabled, CSV values like 42, 3.14, true and false become JSON numbers and booleans instead of strings. Turn it off to keep values such as postal codes or IDs with leading zeros as text.

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