CSV / JSON Converter

About CSV/JSON conversion

How are commas or quotes inside a CSV field handled?

Standard CSV quoting rules (RFC 4180) apply in both directions: a field containing the delimiter, a quote, or a newline is wrapped in double quotes, with any internal quote doubled ("") to escape it.

Does CSV → JSON infer numbers or booleans?

No — every CSV value becomes a JSON string, unchanged. That's deliberate: auto-detecting types would silently turn a zip code like "02134" into 2134, or an ID column into a number that loses precision. Convert the JSON output's fields yourself if you need real numbers.

What happens to nested objects or arrays when converting JSON → CSV?

CSV is flat, so a nested object or array value is stringified as its own JSON snippet inside that cell rather than expanded into extra columns.

What if my CSV has no header row?

Turn off "First row is a header". Not every CSV names its columns, and with the option on the first line of a headerless file would be read as column names and disappear from the data. With it off, CSV → JSON gives you an array of arrays — one array per row, values in column order — rather than an array of objects. It deliberately does not invent names like "column1": a file with no header has no key names, and made-up ones would look like they came from your data.

How do I convert JSON back to CSV without a header row?

The same option controls it. An array of arrays is written out as plain rows, so a headerless file survives a round trip unchanged. An array of objects still uses its keys for column order, but with the option off the row of column names is left out.

What if my JSON records have different keys?

The header row is the union of every key seen across all records, in first-seen order. Records missing a given key just get an empty cell for it.

Can I use a different delimiter, like semicolons or tabs?

Yes — the delimiter selector applies to both reading CSV input and writing CSV output.

Does this tool upload my data anywhere?

No. Parsing and conversion happen entirely in your browser with hand-written code — no network calls. Nothing you paste ever leaves your device.