Open an Excel or CSV file, preview it, then save it as CSV or Excel. Nothing is uploaded.
Only values are converted: formulas are saved as their last calculated result, and formatting, charts, images and macros are dropped. CSV holds one sheet, so each sheet is saved separately. Very large files depend on your device memory, and only the first 50 rows are previewed. Password-protected workbooks cannot be opened. If a CSV shows garbled characters, it was probably saved in a different encoding; re-save it as UTF-8 in your spreadsheet program.
Is my file uploaded? No. It is read and converted locally in your browser.
Will Excel open the CSV correctly? The CSV is saved as UTF-8 with a byte-order mark so accented and Chinese characters show correctly in Excel.
Do formulas survive? No, only the calculated values.
Informational tool, not legal or tax advice.