How to use CSV ↔ JSON
Convert CSV tables and arrays of JSON records.
- Choose a CSV file or paste an array of JSON objects. Preview the result and export. CSV values remain strings to preserve leading zeros.
- Process the selected files, then inspect the preview, dimensions or warnings.
- Download a new copy and check it before replacing or sharing the original.
How processing works
CSV-to-JSON maps header names to string cell values. JSON-to-CSV accepts a non-empty array of flat objects, combines their property names as columns and writes missing values as empty cells.
A quick example
Convert an address table into a JSON array without turning 00123 into 123.
Assumptions, edge cases & limits
- Nested JSON objects and arrays are unsupported.
- CSV exports escape formula-like cells for spreadsheet safety, which can introduce an apostrophe.
- JSON input must be a flat array of objects. Nested objects require a different flattening strategy.
Questions about CSV ↔ JSON
Will CSV to JSON preserve leading-zero IDs as strings?
Yes. CSV cells remain strings, so 00123 is not silently changed to a number. Convert types deliberately later if your receiving system requires numeric values.
Can I convert nested JSON to CSV?
Not directly. Flatten nested objects and arrays into the columns you want before conversion. This tool expects flat objects and does not invent a nesting convention.
Are my files or inputs uploaded?
Calculation and file processing run in your browser without a processing upload. Downloads go to your device. Choosing a next-step transfer creates a temporary local copy for that workflow. Region preferences are stored separately from tool inputs. See our privacy details.
Can I use this tool for free?
Yes. No signup, subscription or payment is required to use the tool or download its output. File tools have device and size limits; a smaller batch may work better on a phone.
A result or explanation needs correcting? Tell us the tool name and an example.