CSV to Excel Converter
Convert CSV files to Excel (.xlsx) format. No character encoding issues, with auto column width.
Drag & drop CSV files
or
Supported formats: CSV / TSV / TXT files supported
What Is CSV to Excel Conversion?
CSV to Excel conversion is an online tool that converts CSV files into Excel format (.xlsx). Since raw CSV files lack column width adjustment and filter capabilities, converting to Excel makes data viewing, editing, and sharing much smoother.
sakutto.ai's CSV to Excel converter processes everything in your browser — your data is never sent to any server. You can safely convert CSV files containing business data and personal information.
With automatic character encoding detection, simply drop a Shift_JIS or UTF-8 CSV file and it converts to Excel instantly. Great for data analysis preparation and internal file sharing. Free, no sign-up required.
How to Use the CSV to Excel Converter
- Drag and drop a CSV file, or use the file picker to load it
- Adjust the Excel output settings as needed (bold headers, auto-fit column widths, sheet name)
- Click the "Convert to Excel" button
- Download the converted Excel file
Features
- No garbled text
- Encoding is auto-detected, so both Shift_JIS and UTF-8 CSV files are converted correctly
- Auto-fit column widths
- Column widths adjust automatically to fit the content, producing a clean and readable Excel file
- Bold headers
- An option to bold the first row as a header improves data readability
- Batch conversion
- Convert multiple CSV files to Excel at once
- 100% browser-based
- Files are never sent to a server — your privacy is protected
Why CSV to Excel Converter on sakutto is safe
Many online tools upload your files to external servers for processing. This tool never sends your CSV files to any server — everything is processed entirely in your browser.
* Some AI-powered tools require server-side processing. Tools that send data to a server will always notify you beforehand.
| Comparison | Typical online tools | sakutto |
|---|---|---|
| Where data is sent | Uploaded to external servers | Nowhere — processed in your browser |
| Data leak risk | Risk during transfer and server storage | No risk — no network transfer occurs |
| External traffic | File data travels over the internet | No file data appears in network logs |
| Offline use | Not possible (server required) | Works offline after initial load |
How browser-based processing works
- WebAssembly (WASM): Processes CSV files in your browser at near-native speed. No server communication occurs.
- Web Workers: Runs on a background thread separate from the main thread, so your browser stays responsive during processing.
- After processing, your browser automatically frees the data from memory. No CSV files remains outside your device.
For IT security teams: How to verify
You can verify that sakutto never sends your CSV files externally by checking the Network tab in your browser's DevTools while using the tool. You'll see that no requests involving your CSV files are made. This can also serve as documentation for your IT security team.
Frequently Asked Questions
Will converting my CSV to Excel cause garbled characters?
No. This tool auto-detects the file's encoding before converting, so CSV files in any encoding — including Shift_JIS and UTF-8 — are converted without garbled text.
What does the converted Excel file look like?
Column widths are automatically adjusted to fit the content. You can also enable bold formatting for the header row (first row) and customize the sheet name.
What file formats are supported?
CSV (comma-separated), TSV (tab-separated), and TXT (text) files are supported. The delimiter is auto-detected.
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