CSV → JSON parses RFC 4180 text (quoted fields, doubled quotes, newlines inside quotes, CRLF) with delimiter auto-detection (comma, semicolon, tab, pipe), header row → objects or arrays, and optional type inference (numbers, booleans, null; leading zeros and unsafe integers stay strings). JSON → CSV takes an array of objects (union of keys) or arrays, stringifies nested values, quotes per RFC 4180 and neutralizes spreadsheet formula injection. Limits: 20,000 rows, 500 columns, 1,000,000 cells. Everything runs locally.
auto detects from the first lines; also used when writing CSV.
yes: objects keyed by header; no: arrays.
Prefix cells starting with = + - @ with an apostrophe.