CSV to XLSX
Convert CSV to Excel (.xlsx) — right in your browser, nothing uploaded.
The .xlsx is built inside your browser — nothing is uploaded.
This free CSV to XLSX tool converts CSV into Excel (.xlsx) entirely inside your browser, so your file never leaves your device. Paste your data and download the finished file with one click. It is free, needs no signup, has no file-size limit beyond your device's memory, and keeps working offline once the page has loaded.
Frequently Asked Questions
How do I convert CSV to Excel (.xlsx)?
Paste your CSV into the box above and the Excel (.xlsx) appears instantly below — there is no button to press and nothing to upload. The whole conversion runs in your browser, so you can copy the result or download it as a file. If the input has a problem, a clear message explains exactly what to fix.
Is this converter free and private?
Yes on both counts. It is completely free with no signup or limits, and it is private because everything happens locally in your browser — your data is never sent to a server. That makes it safe for confidential exports and customer data, and it keeps working offline once the page has loaded.
Will the .xlsx open in Excel and Google Sheets?
Yes. The file is a genuine .xlsx workbook (the same format Excel saves), so Excel, Google Sheets, LibreOffice and Numbers all open it directly. The first row becomes the header row and every value keeps its position, so you can start working with it immediately.
Is there a size limit?
There is no fixed limit because nothing is uploaded — the only real constraint is your device's memory, so even large files convert quickly on a normal computer. Very large inputs are handled more comfortably on a desktop browser than on a phone.
Does it work on mobile and every browser?
Yes. It runs in any modern browser on Windows, Mac, Linux, iPhone and Android with nothing to install, and works offline once loaded. The result can be copied or downloaded on any device.