CSV Encoding Converter
Fix CSV character encoding issues. Convert between Shift_JIS and UTF-8 to resolve garbled text in Excel.
Drag & drop CSV files
or
Supported formats: CSV / TSV / TXT files supported
What Is CSV Encoding Conversion?
CSV encoding conversion is an online tool that converts CSV file character encodings between Shift_JIS, UTF-8, and UTF-8 with BOM. It resolves garbled text when opening CSV files in Excel and facilitates data exchange between different systems.
sakutto.ai's CSV encoding converter processes everything in your browser — your CSV data is never sent to any server. You can safely convert files containing customer lists, sales data, and other sensitive information.
Simply drag and drop a file to auto-detect its current encoding, choose a target encoding, and download. Perfect for fixing Excel garbled text, preparing imports for web services, and adjusting encodings for database integration. Free, no sign-up required.
How to Use the CSV Encoding Converter
- Drag and drop a CSV file, or use the file picker to load it
- The character encoding is detected automatically (Shift_JIS, UTF-8, EUC-JP, etc.)
- Select the target encoding you want to convert to
- Click the "Convert" button to run the conversion
- Download the converted file
When This Tool Comes in Handy
CSV files showing garbled text in Excel
Opening a UTF-8 CSV in Excel often produces garbled characters. Converting to UTF-8 with BOM or Shift_JIS solves the problem.
Exports from web applications
When a web application exports a UTF-8 CSV that needs to be opened in Excel on Windows, this tool converts the encoding for compatibility.
Legacy system compatibility
Convert CSV files created with older encodings like EUC-JP or JIS to modern UTF-8.
Batch conversion of multiple files
Convert multiple CSV files to the same encoding at once — no need to process them one by one.
Why CSV Encoding 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
Why does my CSV file show garbled text in Excel?
Excel tries to open CSV files using the system's default encoding (often Windows-1252 or Shift_JIS). If the file is saved as UTF-8 without a BOM, the characters may appear garbled. Converting to UTF-8 with BOM or Shift_JIS resolves this.
What is UTF-8 with BOM?
BOM (Byte Order Mark) is a special byte sequence at the beginning of a file that signals the encoding is UTF-8. When Excel detects a BOM, it correctly reads the file as UTF-8, preventing garbled characters.
Are my files sent to a server?
No. All processing happens entirely in your browser. Your files are never uploaded to any server.
Which encodings are supported?
Input: UTF-8, Shift_JIS, EUC-JP, and JIS (ISO-2022-JP) are auto-detected. Output: You can choose from UTF-8, UTF-8 with BOM, Shift_JIS, EUC-JP, or JIS.
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