Question 1

How do I convert nested JSON to CSV?

Accepted Answer

Paste your JSON and keep "Flatten nested objects" on. Nested keys become dot-notation columns — {"address":{"city":"London"}} becomes a column address.city. Depth is unlimited, and arrays can become indexed columns, one joined cell, a JSON string, or exploded into multiple rows.

Question 2

Is my data uploaded anywhere?

Accepted Answer

No. All conversion runs in your browser with JavaScript. Your JSON or CSV is never sent to a server and there is no login. Only your option settings — never the data — can be encoded into an optional share link.

Question 3

How are commas, quotes, and newlines inside values handled?

Accepted Answer

The converter follows RFC 4180. Any value containing the delimiter, a double quote, or a line break is wrapped in double quotes, and embedded double quotes are doubled. Excel, Google Sheets, and standard parsers read the file back correctly, including multi-line cells.

Question 4

Can I convert CSV back to JSON?

Accepted Answer

Yes. Switch the direction to CSV → JSON. It auto-detects the delimiter, uses the first row as headers, and can infer types ("123" → number, "true" → boolean). With unflatten on, dot-notation headers like address.city are rebuilt into nested objects.

Question 5

Why enable the UTF-8 BOM for Excel?

Accepted Answer

Excel on Windows may misread UTF-8 files without a byte-order mark, garbling non-ASCII text such as Korean. The BOM option prepends the mark so Excel opens the file in the correct encoding; the CSV → JSON parser strips it automatically.

Question 6

What does "explode arrays into rows" do?

Accepted Answer

Explode emits one row per array element, repeating the other fields, instead of indexed columns. {"id":1,"tag":["x","y"]} becomes two rows: 1,x and 1,y. With several array fields it produces the cartesian product — handy for un-nesting API responses into a flat table.

JSON ↔ CSV Converter

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