CSV ↔ JSON Converter

Details

• Delimiter detection looks at the first lines and picks whichever of comma, semicolon, tab or pipe splits them into the most columns. European Excel exports often use semicolons.
• Type detection is off by default on purpose. With it on, 00123 stays a string, but 123 becomes a number and empty cells become null. Leave it off for ZIP codes, phone numbers and IDs.
• JSON → CSV uses the union of all keys as columns, in first-seen order. Nested objects are written as JSON text inside the cell.

FAQ

How large a file can I convert?

It depends on your device memory. Files of tens of megabytes usually work because nothing is uploaded; the file is read locally.

Does it handle line breaks inside a cell?

Yes, as long as the cell is wrapped in double quotes, as the CSV standard requires.