In short: A CSV to JSON converter turns rows of comma-separated values into an array of JSON objects keyed by the header row, and converts JSON arrays back into CSV with nested keys flattened.
About CSV ⇄ JSON Converter
CSV is the lingua franca of spreadsheets and data exports, while JSON is what APIs and JavaScript expect. Converting between them looks trivial until a field contains a comma, a quote or a line break. This converter implements proper RFC 4180 parsing, so "Smith, Anna" stays one value and doubled quotes inside fields are unescaped correctly.
CSV → JSON produces an array of objects keyed by the header row (or arrays of values if there is no header), optionally turning numeric strings into numbers and true/false into booleans. JSON → CSV takes an array of objects, collects every key that appears in any row as a column, flattens nested objects using dot notation like address.city, and quotes values only when needed.
How to use CSV ⇄ JSON Converter
- Paste CSV or a JSON array into the input box.
- Pick the delimiter — semicolons are common in European Excel exports, tabs when copying from a spreadsheet.
- Press CSV → JSON or JSON → CSV.
- Copy the output or download it as a file.
Examples
The sample CSV becomes [{"name":"Smith, Anna","city":"Lisbon","age":34}, …] — note the comma inside the quoted name is preserved.
[{"id":1,"user":{"name":"Ana"}}] becomes a CSV with columns id and user.name.
Frequently asked questions
Why do my accented characters look wrong in Excel?
Excel sometimes assumes a legacy encoding when opening CSV. The CSV download includes a UTF-8 byte-order mark so Excel detects UTF-8 correctly.
Can I keep leading zeros like ZIP codes?
Untick Convert numbers to keep every value as text, so 02139 does not become 2139.
How are arrays inside JSON handled?
Arrays are written into a single CSV cell as JSON text, since CSV has no native list type.
Is there a size limit?
No fixed limit; files of a few megabytes convert instantly. Everything runs locally.
Updated November 2026 · Free, no signup · How we build and test tools