Koala Excel to JSON

Convert Excel files to JSON instantly — no signup, no upload, no limits. Drop your .xlsx or .xls file, pick a sheet, and get a formatted JSON array of objects. The first row becomes field names (keys), and each subsequent row becomes an object. Numbers, dates, and booleans are auto-typed. Everything runs locally in your browser — your spreadsheet data never leaves your device.

How does Excel to JSON conversion work?

The first row of your spreadsheet becomes the JSON keys (field names). Each subsequent row becomes a JSON object in the output array. Numbers, booleans, and dates are auto-detected and typed correctly.

Can I convert a specific sheet?

Yes. If your workbook has multiple sheets, a sheet selector appears so you can choose which one to convert. Each sheet generates its own JSON array.

Is the JSON output formatted?

Yes. The JSON is formatted with 2-space indentation by default. You can switch between formatted and minified (compact) output depending on your use case.

Does my file leave my device?

No. The Excel file is parsed entirely in your browser using a client-side spreadsheet engine. No data is uploaded, stored, or sent anywhere.