Text, Data & Code tool
CSV & JSON Converter
Convert between CSV and JSON with your chosen separator, header handling and clear warnings. Keep CSV cells as text to preserve leading zeros and identifiers.
From rows to records—and back.
Convert CSV to JSON strings, or a flat JSON table to CSV. Nothing is uploaded by this tool.
Cells stay as text, including blanks, dates and leading zeros. Quoted commas, line breaks and doubled quotes are supported.
0 / 2,000,000 characters
No automatic repairs, code execution, tracking fields or branding are added to your data. Clear removes the working text from this tool. JSON is limited to 100 nesting levels; tables to 50,000 rows / 200,000 cells.
Processed privately in your browser — your entries are not uploaded.
Good to know
How this tool works
Choose a conversion direction and CSV separator. CSV to JSON keeps every cell as a string; use the header option for named records or turn it off for arrays of cells. JSON to CSV accepts flat objects or equally sized arrays, not nested records. Output is UTF-8. Copy and download include the full result even when the preview is shortened.
Frequently asked questions
What is CSV & JSON Converter useful for?
Convert CSV tables to JSON and flat JSON records back to CSV. Validate a small sample before processing important data, and keep a copy of the original input.
Is my information stored?
Your text is processed locally in a browser worker. It is not uploaded by this tool or saved in browser storage. Clear releases the working input and result. Downloads remain in your normal download folder.
Will large numbers or leading zeros change?
JSON number tokens are kept exactly as written. CSV imports produce JSON strings, so leading zeros remain. Spreadsheet software may reinterpret CSV values when opened; import columns as text to protect IDs and long numbers.
What does formula protection do?
CSV export can prefix formula-like cells with an apostrophe to help prevent spreadsheet execution. This changes those cells, including negative numbers. The result reports how many were changed. Turn it off only when exact raw cells are needed and the data is trusted.
Can CSV keep all JSON information?
No. CSV has no native value types. Null and missing fields become empty cells, nested structures are rejected, and arrays of objects use the union of their columns in first-seen order. The converter explains these limitations rather than silently guessing.