The Data Transmuter
JSON to CSV. CSV to JSON. Instant.
A JSON-to-CSV converter turns an array of objects into a comma-separated table: every unique key becomes a column header and every object becomes a row. Paste [{"name":"Ada","role":"CEO"}] and you get two lines, name,role then Ada,CEO. It also runs in reverse, reading the header row and mapping each line back to an object. Everything happens in your browser, so your data never leaves the page.
How the conversion works
JSON to CSV: collect the union of keys across
all objects as the header, then write one row per object. A
value that holds a comma, a double quote, or a newline is
wrapped in double quotes, and inner quotes are doubled.
CSV to JSON: read the first line as the keys,
then map each following line to an object, turning true, false,
and numeric text into real booleans and numbers.
Reference conversions
| JSON input | CSV output |
|---|---|
[{"name":"Ada","role":"CEO"}] | name,role Ada,CEO |
[{"id":1,"plan":"Pro"},{"id":2,"plan":"Free"}] | id,plan 1,Pro 2,Free |
[{"city":"Paris, FR","zip":75001}] | city,zip "Paris, FR",75001 |
How it works
Paste your Input Data (JSON or CSV).
Click the Convert button.
Copy the Clean Output.
Why it matters
Data formats are messy. Sometimes you need a spreadsheet, sometimes you need an API payload.
This tool runs entirely in your browser. Your data is never sent to a server.
The Logic
JSON to CSV: Flattens the object array,
extracts unique keys as headers, and maps values to rows.
CSV to JSON: Parses the header row, then
maps each subsequent row to an object using those keys.