CSV to Excel Converter
Paste CSV data or upload a .csv file and download a real .xlsx Excel spreadsheet — generated entirely in your browser.
CSV Input
Frequently Asked Questions
Does this create a real .xlsx file?
Yes. This tool generates a valid Open XML (.xlsx) file that opens correctly in Microsoft Excel, Google Sheets, LibreOffice Calc, and all major spreadsheet apps.
Is my data sent to a server?
No. The .xlsx file is generated entirely in your browser. Your data never leaves your device.
What delimiters are supported?
Comma (,), semicolon (;), tab, and pipe (|). The tool also auto-detects the delimiter if you leave it set to Auto.
Can I add a header row?
The first row of your CSV is treated as a header row and formatted in bold in the Excel output.
CSV vs XLSX: When to Convert
| Feature | CSV | XLSX |
|---|---|---|
| Format | Plain text | Binary / ZIP (Open XML) |
| Multiple sheets | No — single table | Yes |
| Formulas | No | Yes |
| Charts | No | Yes |
| Cell formatting | No | Yes (fonts, colors, borders) |
| Data types | All text | Numbers, dates, booleans |
| Max rows | Unlimited | 1,048,576 |
| File size | Very small | Larger (compressed ZIP) |
| Interoperability | Universal | Microsoft Office ecosystem |
What is an XLSX File?
An .xlsx file is a ZIP archive containing XML files. You can verify this by renaming any .xlsxto .zipand extracting it — you'll find xl/worksheets/sheet1.xmlcontaining the actual cell data, plus metadata, shared strings, and styles files.
The Open XML format (ECMA-376 / ISO 29500) is the same format used by .docx (Word) and .pptx (PowerPoint). This tool generates it client-side using theExcelJSor SheetJS library.