CSV to XLSX Converter
Convert Comma-Separated Values (CSV) to Office Open XML Spreadsheet (XLSX) online for free. Runs 100% in your browser. Files never leave your device. No signup, no watermarks, no limits.
Drag & drop files here
or
Choose filesProcessed on your device. Nothing is uploaded
How to CSV to XLSX convert files
- 01Add your files
Click “Choose Files” or drag and drop them onto the page. Batch conversion is supported.
- 02Adjust settings
Pick quality, size or other options. Sensible defaults are pre-selected.
- 03Convert & download
Hit Convert and download your files. Everything runs locally. Nothing is uploaded.
What is a CSV (Comma-Separated Values) file?
CSV is the simplest spreadsheet interchange format. One row per line, values separated by commas. Every spreadsheet app and programming language can read it.
- Developed by
- Unknown
- Initial release
- 1972
What is a XLSX (Office Open XML Spreadsheet) file?
XLSX is the default Microsoft Excel format since Office 2007. Converting XLSX to CSV makes the data usable in scripts, databases and other apps.
- Developed by
- Microsoft
- Initial release
- 2007
Frequently asked questions
How do I convert CSV to XLSX?
Click “Choose Files” or drag your CSV file onto the page, optionally adjust the settings, then hit Convert. Your XLSX file downloads straight from your browser. Nothing is uploaded anywhere.
Is this CSV to XLSX converter free?
Yes, completely free with no hidden limits, watermarks or signup. Because all processing happens on your own device, there are no server costs to pass on to you.
Are my files uploaded to a server?
No. The conversion engine runs entirely in your web browser using WebAssembly. Your files never leave your device. You can even disconnect from the internet after the page loads and keep converting.
Is there a file size limit?
We impose no fixed limit. The practical ceiling is your device's free memory, since processing happens locally. Most conversions work comfortably with files up to a few hundred megabytes, and image or document conversions handle much more.
Does it work on my phone?
Yes. The converter runs in any modern browser on Windows, macOS, Linux, Android and iOS. No app installation is required.