CSV to JSON converter

File stays on your device

Paste CSV or drop a .csv file to get a JSON array of objects keyed by the header row. Quoted fields, commas inside quotes, and semicolon or tab delimiters are handled, and numbers and true/false become real JSON types.

Fill in the fields to see the result.

How to use it

Paste CSV or drop a .csv/.tsv file (up to 5 MB).
Keep 'header' on to get objects, or off for arrays; choose whether to convert types.
Copy the JSON or download it as a .json file.

Details

Parsing: RFC 4180 quotes and escaped quotes, line breaks inside quotes
Delimiter: Comma, semicolon, tab or pipe, detected from the first lines
Types: Numbers, true/false and empty cells (null) when enabled; leading zeros kept as text

Questions

My Excel CSV uses semicolons. Will it work?

Yes. Excel in many European locales saves with semicolons and decimal commas; the delimiter is detected. Decimal commas stay as text so nothing is misread.

Why are ZIP codes or IDs kept as strings?

Values with leading zeros, like 02134, would lose the zero as numbers, so they stay text. Turn off type conversion to keep every value as a string.

What if rows have different numbers of cells?

The JSON is still produced, missing cells become empty, and a warning tells you how many rows didn't match the header.

Can I convert JSON back to CSV?

Not on this page yet. The MCP server's json tool has to_csv, and the same converter will be added here.

Is what I type sent anywhere?

No. The calculation runs in this browser tab with the same code our MCP server uses. Nothing you type is sent to a server or saved, apart from settings like filing status, which stay in this browser.

Can an AI agent use this?

Yes. The same function is a tool on our free MCP server at tools.cuelark.com/mcp, so ChatGPT, Claude or Cursor get exactly the answer this page shows. 'Copy MCP call' gives you the arguments.