When do I need to convert between CSV and JSON?

Spreadsheets and old data feeds use CSV; modern APIs use JSON. Importing CSV into a JSON-based pipeline (or exporting JSON to a CSV for analysts) is a routine task.

How does the tool handle quoted CSV fields?

CSV with quoted fields (containing commas or newlines) is parsed correctly. Embedded quotes use the standard escape ("") format. The tool follows RFC 4180 for parsing.

What happens with nested JSON when converting to CSV?

CSV is flat by nature. The converter offers two strategies: flatten nested keys with dot notation (user.name) or stringify nested values as JSON in a single cell. Pick based on what your spreadsheet expects.

Can the tool handle large files?

Yes, up to several megabytes in modern browsers. For multi-gigabyte files, use a streaming tool like Miller (mlr) or pandas instead.

Does my data get uploaded?

No. Conversion runs entirely in your browser. Your data never leaves your machine.

TOOLS/ CSV ↔ JSON100% Local

CSV ↔ JSON

Two-way converter. Header-aware (first row treated as field names), handles quoted values with embedded commas, supports both array-of-objects and array-of-arrays JSON output. Pick a direction below.

Separator: First row is header Indent: Output as array of objects

CSV input

JSON output

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