UsefulTab
CSV to Excel
Convert a CSV into a real .xlsx workbook — locally, no upload.
Add a CSV to convert it to Excel
Drop a file or paste CSV text, then click Convert to build a downloadable .xlsx — all in your browser.
Runs entirely in your browserConvert CSV to a real .xlsx, privately
Drop a .csv file or paste CSV text, and it is assembled into a genuine Excel workbook (.xlsx) — a zipped set of the XML parts Excel expects, built in your browser. Values that look numeric are written as real number cells so Excel treats them as numbers, not text. Because nothing is uploaded, this is a strong fit for confidential customer or financial exports.
Common questions
Is the output a real Excel file?
Yes. It produces a valid .xlsx — the Open Packaging Convention zip of worksheet, workbook, and relationship XML that Excel, Google Sheets, and LibreOffice all open natively. It is not a renamed CSV.
Do numbers stay numeric?
Yes. Cells whose value parses cleanly as a number are written as numeric cells, so Excel can sum and chart them. Everything else is written as text, preserving leading zeros and codes.
What about quoted fields and delimiters?
The CSV parser handles quoted fields with embedded commas and newlines, and you can pick comma, semicolon, or tab as the delimiter. The first row becomes the worksheet's first row.
Is my data uploaded anywhere?
No. Parsing and workbook assembly happen entirely in your browser. Nothing is sent to a server, which makes it safe for sensitive spreadsheets.