CSV ⇄ JSON

Convert spreadsheets to JSON and back without uploading anything. CSV → JSON uses the header row as object keys; with "infer types" on, numbers, booleans and nulls are parsed instead of left as strings. JSON → CSV flattens an array of objects, taking the union of all keys as columns.

The parser handles quoted fields, embedded commas and escaped quotes (RFC 4180). Switch direction to round-trip the result in one click. Everything runs locally in your browser.