What JSON structure does CSV to JSON produce?

With 'First row is header' checked, each data row becomes a JSON object keyed by the header names — an array of objects. Unchecked, the output is an array of arrays with every row as a plain list of values.

How does number and boolean detection work?

Values that look like numbers become JSON numbers and true/false become booleans; everything else stays a string. Quoted CSV values always stay strings, so codes like 007 keep their leading zeros. The option can be turned off.

🔀 CSV ↔ JSON Converter

Paste CSV to get JSON, or JSON to get CSV — quoted fields, custom delimiters and type detection handled, entirely in your browser.

Frequently Asked Questions

What JSON structure does CSV → JSON produce?

With "First row is header" checked (the default), each data row becomes a JSON object keyed by the header names — an array of objects, the format most APIs and libraries expect. Unchecked, the output is an array of arrays with every row (including the first) as a plain list of values.

Are quoted fields with commas or line breaks handled?

Yes. The parser follows the RFC 4180 conventions: fields wrapped in double quotes may contain the delimiter, line breaks and doubled quotes (""), and they are unwrapped correctly. The JSON → CSV direction applies the same quoting automatically whenever a value needs it.

Which delimiters are supported?

Comma, semicolon (common in European Excel exports), tab (TSV files) and pipe. Auto-detect counts each candidate in the first row outside quotes and picks the most frequent one, so most files convert without touching the setting.

How does "Detect numbers & booleans" work?

Values that look like numbers (42, -3.14) become JSON numbers and true/false become booleans; everything else stays a string. Values that were quoted in the CSV always stay strings, so codes like "007" keep their leading zeros. Turn the option off to keep every value as a string.

What JSON can be converted to CSV?

An array of objects (columns from the union of all keys) or an array of arrays. Nested objects or arrays inside a cell are serialised as JSON strings, since CSV has no nesting. A single object is treated as a one-row table.

Is my data uploaded anywhere?

No. The conversion runs entirely in your browser with JavaScript — your CSV or JSON never leaves your device, so it is safe for customer lists, exports and other sensitive data.