Why are some columns empty?

Objects with different keys produce the union of all keys as the header. Any row missing that key is legitimately empty, and CSV has no null — an empty cell means whatever your importer decides it means.

Can I convert nested JSON?

Not directly — nested objects and arrays do not map onto a flat grid. Flatten to dotted or prefixed keys first, then convert.

Excel shows my numbers as dates. What is happening?

That is Excel guessing at import, not the conversion. Quote the column, prefix it, or import through the data importer with the column type set to text.

Will a comma inside a value break the file?

No — values containing a comma, quote or newline are quoted automatically, and embedded quotes are doubled per RFC 4180.

Text & Data Ready to use

JSON to CSV Converter

Flatten an array of JSON objects into CSV with a header row, chosen delimiter and controlled quoting. Runs in your browser, so no upload step.

JSON input (array of flat objects)

Include header row

Delimiter

Quoting

Fields containing the delimiter, quotes, or line breaks are always quoted (RFC 4180).

This tool runs entirely in your browser. Your input never leaves your device.

About JSON to CSV Converter

The shape that converts cleanly is an array of flat objects — the same thing a CSV becomes read in — and this tool turns it back: the union of every key across the array becomes the header, each object a row, missing keys empty cells. Nested objects and arrays are not dropped or crashed on; stringify them first if you need them in a column.

Quoting follows the rule that breaks spreadsheet imports most often. Auto mode quotes only what must be quoted — a comma, a quote, a newline — and doubles any embedded quote character, so 'He said "hi"' survives the round trip instead of splitting into three columns. Minimal and All give you control when a particular importer is fussy, and the delimiter field covers semicolon and tab files.

The whole pass is local to the browser, so it can be used on an export you would not upload to a converter site. For large payloads, keep the JSON in the range of a few tens of thousands of rows and the conversion stays instant.