CSV ⇄ JSON Converter

Both directions, correct quoting, your choice of delimiter. Runs entirely in your browser, nothing is sent anywhere. ← Workbench

Input — CSV or JSON (auto-detected)

first row is a header detect numbers / booleans Ctrl+Enter converts

Result

How the conversion works

Direction is auto-detected: input starting with [ or { is treated as JSON, anything else as CSV.
CSV is parsed per RFC 4180: quoted fields, "" escapes, commas, tabs, pipes and line breaks inside quoted fields all survive. A byte-order mark at the start is ignored.
Delimiter sniffing: in auto mode the delimiter whose columns come out most consistent wins (, ; tab |).
Header handling: with “first row is a header” checked, CSV becomes an array of objects; duplicates get _2, _3… suffixes and unnamed columns become column3. Uncheck it for a plain array of arrays.
Type detection (optional): cells that are exactly numbers become JSON numbers, true/false become booleans, empty cells become null. Integers beyond ±2⁵³−1 stay strings so they never lose precision; 007 stays a string too.
JSON → CSV: an array of objects becomes a table with columns in order of first appearance; nested objects and arrays are serialized as JSON text in their cell; null becomes an empty cell. An array of arrays converts without a header row.
Anything odd is reported — ragged rows, skipped blank lines, dropped extra cells — in the yellow notes above the result.