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CSV ⇄ JSON TOOL

CSV ⇄ JSON Converter

Turn CSV into JSON, or JSON back into CSV. Paste or drop a file and convert it instantly — with full control over typing, nesting and JSON Lines output.

100% in-browserNo signupFreeJSON Lines ready
CSV ⇄ JSON converterruns in your browser
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How to use it (3 steps)

  1. Load your CSVPaste the text or choose a file. Tell the tool whether the first row is a header, and which delimiter is used (comma, semicolon or tab).
  2. Pick your optionsChoose the output shape (array of objects, array of arrays, or JSON Lines), indentation, number/boolean typing, and whether dot keys become nested objects.
  3. Convert and savePress Convert, review the output, then copy it or download it as .json / .csv.

What makes it different

Both directions

CSV to JSON and JSON to CSV, in the same page. Just switch tabs.

Types that survive the round trip

Leading zeros like "001" stay strings, "42" becomes a number. No silent type damage.

Nesting and flattening

Turn address.city headers into real nested objects — or flatten nested JSON into dot-notation columns.

JSON Lines support

Export one record per line as NDJSON / JSONL, ready for log pipelines and BigQuery.

Handles messy dialects

Delimiters are detected automatically, so semicolon-separated European CSVs and tab-separated exports read correctly.

Nothing leaves the browser

All conversion happens locally. Your file is never uploaded to a server.

Frequently asked questions

My numbers all come out as strings.
Turn on “type numbers & booleans”. Values with a leading zero, such as "001", are deliberately kept as strings so you do not lose the zero.
Does it handle semicolon-separated CSV?
Yes. Delimiters can be auto-detected, or set explicitly to comma, semicolon, tab or pipe.
Can I turn nested JSON into CSV?
Yes. Objects are flattened with dot notation (address.city) and arrays are stored as a JSON string in a single cell.
Is there a size limit?
It runs within your browser's memory. Tens of thousands of rows is a comfortable range.
Is my data uploaded?
No. Everything runs locally in your browser and is never sent to a server.