Takes the Shift_JIS CSV your version of Excel wrote and returns clean UTF-8. Encoding is detected automatically and garbled cells are counted so you know whether it worked.
No uploadNo sign-upEncoding auto-detected
Process your CSVRuns on your device
Drop a CSV here
or click to choose · Shift_JIS / UTF-8 detected
How to use
Drop the CSV (pasting works too).
If needed, force the input encoding to Shift_JIS or EUC-JP.
Press Run, confirm the mojibake count is 0, then download.
What this tool does not do
Writing Shift_JIS is not possible — browsers can only encode UTF-8, so conversion is one-way. If a system insists on Shift_JIS, save the UTF-8 file and re-export it from Excel as CSV.
FAQ
The text is still garbled
Force the input encoding to Shift_JIS or EUC-JP and run again — that fixes a wrong auto-detection.
Should I add a BOM?
Yes if you want Excel to open it cleanly. Leave it off when a script will read the file.
Excel shows mojibake for my UTF-8 file
Excel guesses Shift_JIS. Re-save with the BOM option on and it opens correctly.
Is EUC-JP supported?
Yes, both for auto-detection and as a manual choice.
Is anything uploaded?
No — decoding happens in your browser with TextDecoder.