CSV to XLSX Converter
Free online CSV to XLSX converter. Convert CSV files to Excel workbooks in your browser. Multiple sheets, auto delimiter detection, UTF-8/GBK support. No upload, 100% private.
How do I convert a CSV file to XLSX?
Add your CSV files, adjust the delimiter and output mode if needed, then click Convert to XLSX. The generated workbook downloads immediately.
Is my data uploaded to a server?
No. The entire conversion runs locally in your browser using JavaScript. Your files never leave your device, which makes the tool safe for sensitive data.
Can I convert multiple CSV files at once?
Yes. Add as many CSV files as you like and either merge them into one workbook with multiple sheets or generate one workbook per file.
How is the delimiter detected?
The tool counts commas, semicolons, tabs and pipes in your data and picks the most frequent one. You can also choose the delimiter manually.
Which encodings are supported?
Files are decoded as UTF-8 first. If that fails, GBK is tried, which covers most Chinese-encoded exports from legacy systems.
Can I rename the sheets?
Yes. Each added file has an editable sheet name field, so you can name the sheets before converting.
Are formulas or special characters preserved?
All fields are written as cell values, so numbers, dates as text and quoted content are preserved. CSV has no formulas, so none are created.
Is there a file size limit?
There is no hard limit, but files above 20 MB may take a few seconds to convert because everything is processed locally in your browser.
How to Use CSV to XLSX Converter
CSV to XLSX Converter turns comma-, semicolon- or tab-separated files into real Excel workbooks (.xlsx) entirely inside your browser. Files are parsed, converted and downloaded locally — nothing is ever uploaded to a server, so confidential exports stay on your device.
- Drag and drop one or more CSV files onto the drop zone, or click it to browse. Each file appears in the list with an editable sheet name field and its detected row and column count.
- Pick the delimiter: Auto detect counts commas, semicolons, tabs and pipes and picks the most frequent one, or force a specific delimiter from the select box.
- Choose the output mode — merge everything into one workbook with multiple sheets, or generate one workbook per file.
- Rename sheets by editing the sheet name inputs, then press Convert to XLSX. The workbook (or a ZIP with one workbook per file) downloads automatically.
- Use Clear all to remove every file and start over.
Legacy exports that show garbled characters are usually GBK-encoded — the converter tries UTF-8 first and falls back to GBK automatically, so most Chinese system exports just work.
Related Tools
- CSV to JSON Converter Convert CSV to JSON online free. Supports custom delimiters, header-based objects, auto type detection. All processing in browser.
- Excel to CSV Convert Excel files to CSV online for free. Upload .xlsx, .xlsm or .xls, pick a worksheet, set delimiter, encoding and line endings, then download the CSV.
- CSV to TSV Converter Convert CSV files to TSV format instantly. Free online tool with custom delimiters, quote handling, and 100% browser-based processing.
- CSV to HTML Table Free online CSV to HTML table converter. Paste CSV data and instantly generate clean HTML table code with header row, custom delimiters, styling options, and live preview.
- CSV to YAML Converter Convert CSV data to YAML format online. Supports custom delimiters, header rows, and configurable indentation. Quote-aware parsing handles complex CSV data.
- Signature Generator Free online signature generator. Draw your signature with mouse, finger or stylus, or type it in a handwriting font, then download a transparent PNG ready to insert into PDF and Word documents.
- LaTeX Equation Editor Free online LaTeX equation editor with real-time KaTeX preview. Write, edit, and export math formulas instantly.
- Copybook Generator Generate Chinese character copybook and tracing sheets for handwriting practice. Customize grid styles, sizes, and export as PNG or PDF.