CSV ⇄ JSON Converter
Convert CSV or TSV to JSON and JSON back to CSV or TSV. Handles quoted fields, line breaks in cells, UTF-8 BOM, delimiter detection and Shift_JIS, and lets you pick, reorder and rename columns.
- Runs in your browser (no upload)
Up to 5 MB per file
Paste text or open a file (up to 5 MB).
Choose, reorder and rename columns (3 columns)
Unchecked columns are left out. Use the arrows to change the order. Enter an output name to rename a column (leave it empty to keep the original name).
Result
How to use
- Choose the direction: CSV → JSON or JSON → CSV.
- Paste your data or open a file. For CSV you can pick the delimiter and whether the first row holds the field names.
- If needed, open "Choose, reorder and rename columns" to decide which columns to output, their order and their names.
- Check the result, then copy it or download it as a file.
FAQ
Are line breaks, commas and quotes inside cells supported?
Yes. Quoted values are read following RFC 4180, including line breaks, commas and doubled quotes (""). When writing CSV, only values that need it are quoted.
Can I output only some columns or rename keys?
Yes. In "Choose, reorder and rename columns" you can uncheck columns, move them with the arrows and enter output names. Clashing output names are reported as an error.
What happens to nested JSON data?
Objects and arrays are written as JSON text in a single cell. The columns are the union of all object keys, in the order they first appear.
The text looks garbled in Excel.
Download with "Add a BOM" turned on so Excel recognizes UTF-8. When reading a Shift_JIS CSV, choose Shift_JIS as the file encoding.
Notes & limitations
- What you enter is processed only on this page and is not sent to YUCTS servers.
- Input is limited to 5 MB.
- By default, text starting with =, +, - or @ (but not plain numbers) is written with a leading ' to prevent formula injection. You can turn this off for data read by programs.
- Numbers and true/false are converted only when the value stays exactly the same; dates and other types are not detected.
- Numbers with more than 15 digits are written with all their digits, but some spreadsheets round them when opening the file.
Data sources
- RFC 4180: Common Format and MIME Type for Comma-Separated Values (CSV) Files(opens in a new tab) — Checked on: 2026-10-31
- RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format(opens in a new tab) — Checked on: 2026-10-31
- OWASP: CSV Injection(opens in a new tab) — Checked on: 2026-10-31
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