Otter Excel to CSV

Convert Excel spreadsheets to CSV format online — no signup, no upload, no limits. Drop your .xlsx or .xls file, pick a sheet if it's a multi-sheet workbook, preview the CSV output, and download. Everything runs locally in your browser using a client-side spreadsheet engine. Safe for sensitive financial data, customer lists, and business reports.

How do I convert Excel to CSV?

Drop your .xlsx or .xls file into the tool. If the workbook has multiple sheets, select the one you want. Preview the data, then click Download CSV. The file is converted instantly in your browser.

Does it support multi-sheet workbooks?

Yes. When you load a multi-sheet Excel file, a sheet selector appears so you can pick which sheet to convert. You can also download all sheets as separate CSV files with one click.

Is my data uploaded to a server?

No. Everything runs in your browser using a client-side spreadsheet engine. Your Excel file never leaves your device.

What Excel formats are supported?

The tool supports .xlsx (Excel 2007+), .xls (Excel 97-2003), and .ods (OpenDocument). All are converted to standard RFC 4180 CSV.