CSV / JSON Converter

CSV and JSON conversion

CSV is widely used for spreadsheets and exports, while JSON is common in APIs and application data. This tool converts between the two formats directly in your browser.

How to convert

1. Choose CSV → JSON or JSON → CSV.
2. Paste the source data into the input editor, or upload a .csv, .tsv, or .json file.
3. Choose a delimiter, or leave it on auto-detect so the tool picks the most frequent one outside quoted fields.
4. For CSV, select whether the first row contains headers and whether primitive types should be detected.
5. Convert, copy, or download the result as JSON, CSV, or Excel.

Quoted CSV fields may contain commas, quotes, and line breaks. JSON conversion accepts an array of objects, combines their fields into columns, and serializes nested values as JSON text.

Table preview

Both directions offer a table view. Switching the CSV input or the CSV output to table mode shows the parsed rows with headers, which makes it easy to confirm the delimiter and header settings before exporting.

Column mapping

In CSV → JSON mode, enable column mapping to keep only chosen columns, rename their JSON keys, and reorder them. The output JSON uses the mapped order and names, and the Excel export follows the same mapping.

Invalid rows

Rows whose field count does not match the header are skipped and listed with their line numbers, so one bad row does not break the whole conversion. Unclosed quotes and duplicate headers are reported as hard errors.

Excel export

Excel export writes a real .xlsx file using an internal writer, with no spreadsheet library and no upload. The current table (including any column mapping) becomes the sheet.

Privacy and limits

Parsing and conversion happen entirely in your browser. Input is limited to 1 MB, and no CSV or JSON content is uploaded or stored.