Processed locally — your file never leaves your device
Excel to CSV Converter
Convert an XLSX workbook sheet to a CSV file, entirely in your browser.
Excel
Drop a spreadsheet or data file hereor click to choose a file from your deviceNothing is uploaded — everything happens on your device.
How it works
- Select or drop a .xlsx file.
- Your browser reads the workbook locally — nothing is uploaded.
- Choose a sheet if the workbook has more than one.
- A .csv file is built from that sheet's data, entirely on your device, ready to download.
Frequently asked questions
- Is my Excel file uploaded to a server?
- No. The workbook is read and converted entirely on your device using WebAssembly-based processing — nothing is sent anywhere.
- What if my workbook has multiple sheets?
- You'll be able to choose which sheet to convert; only one sheet becomes the output CSV.
- What happens to formulas and dates?
- Formulas are converted using their last calculated value, and dates are written out in a standard format — both are called out with a notice so you know before downloading.
- Are merged cells preserved?
- A merged range is flattened into its top-left cell's value in the CSV output, since CSV has no concept of merged cells. You'll see a warning when this happens.
- Is there a file size limit?
- There's no server upload limit. The practical maximum depends on your device's memory and browser.