myriadfile

CSV to JSON converter

Turn CSV rows into JSON objects for code and APIs. Your files stay on this device.

Drop CSV files here Files, a whole folder or a ZIP. Nothing leaves your device.

How to convert CSV to JSON

  1. Add your files. Drop CSV files anywhere on the page, or use Choose files. Folders and ZIP archives work too; every CSV inside is picked up.
  2. Check that JSON is selected. JSON is already chosen on this page. Other formats in the same row are one tap away if you change your mind.
  3. Adjust options if you need to. For workbooks with several sheets, choose every sheet or only the first.
  4. Convert and download. Press Convert. Each file shows its progress, then a Download button. With several files, “Download all” gives you a single ZIP.

What happens to your CSV

The CSV is read with SheetJS and each row becomes a record, using the first row as field names. Every sheet of the workbook is converted; for single-sheet formats such as CSV you get one file per sheet, or you can choose the first sheet only.

Numbers and true/false values keep their types and dates are written in ISO format. Formulas are converted to their calculated values.

About CSV and JSON

CSV: CSV is a plain-text table with commas between values. Every spreadsheet, database and analytics tool can import it.

JSON: JSON is a text format for structured data used by almost every web API and app.

Questions

Is my CSV file uploaded anywhere?

No. The conversion runs inside this browser tab using code served by this site, and the JSON is created on your device. You can even disconnect from the internet once the page and its converter have loaded.

What happens to formulas and multiple sheets?

Formulas are saved as their calculated values. Multi-sheet workbooks keep every sheet in formats that support it; CSV, TSV, JSON and similar formats get one file per sheet, or a single object keyed by sheet name.

Can I convert several CSV files at once?

Yes. Drop as many CSV files as you like, a whole folder or a ZIP. They convert one after another, and “Download all” saves every JSON in one ZIP that keeps your folder structure.

Is there a file size limit?

There is no fixed limit, because nothing is uploaded. The practical limit is your device’s memory: a phone may struggle with very large files that a laptop converts easily.