CSV ↔ JSON converter

What it does

Convert CSV and flat JSON with delimiter controls, source-positioned CSV errors, previews and local downloads.

How to use it

1. Paste data or choose a CSV, TSV or JSON file. Choose comma, semicolon, tab or pipe delimiters.
2. CSV with headers becomes objects; without headers it becomes arrays. CSV values remain strings, preserving leading zeros. JSON must be an array of flat objects or arrays.
3. Spreadsheet protection prefixes formula-like CSV cells with an apostrophe. Disable only when you need exact cell text and trust the data.
4. CSV errors identify logical records and physical source lines, including quoted multiline fields. Review up to 25 issues and fix the source; invalid CSV does not produce a partial conversion.

Example

CSV name,score followed by Alex,42 becomes [{"name":"Alex","score":"42"}] with headers enabled.

Methodology

Papa Parse handles quoting and delimiters. CSV diagnostics identify logical records and physical source lines, with character or field positions when available, while accounting for quoted multiline records and skipped blank lines. JSON parsing accepts flat scalar rows; object exports use the union of keys with blanks for absent values.

Limitations

200,000 input characters, 800 KB file size, 10,000 rows and 100 columns. Headers must be unique and non-empty. At most 25 CSV issues are shown; invalid input produces no partial conversion. Output is bounded to 2 million characters. Nested JSON is unsupported; JavaScript number precision applies.

Automation

This tool runs in your browser. No upload API or MCP endpoint is available.