KoguNavi

CSV Mojibake Repair (Encoding Checker)

Open a garbled CSV, see which encoding it really uses, and download an Excel-safe UTF-8 copy without the file ever leaving your browser.

Conversion tools

What it helps with

  • Fix a CSV that opens as mojibake in Excel
  • Check whether a CSV is Shift_JIS or UTF-8 before importing
  • Convert legacy Shift_JIS exports to UTF-8 safely

How to use

  1. Choose or drop the CSV file that shows garbled characters.
  2. Check the detected encoding and the decoded preview rows.
  3. Download the UTF-8 (with BOM) copy and open it in Excel.

Examples

Excel shows mojibake

Input

meibo.csv (Shift_JIS)

Output

Detected: Shift_JIS → download UTF-8 (BOM)

UTF-8 CSV for Excel

Input

export.csv (UTF-8 without BOM)

Output

Detected: UTF-8 → download UTF-8 (BOM)

Good to know

  • Export is UTF-8 with BOM only; saving as Shift_JIS is not supported yet.
  • Encoding detection is heuristic and can be uncertain for very short or heavily damaged files.
  • Files over 8 MB are rejected to keep the browser responsive.

FAQ

Why does my CSV look garbled in Excel?
Excel on Japanese Windows assumes Shift_JIS for CSV files without a BOM, so UTF-8 files without a BOM often show mojibake. A UTF-8 file with a BOM opens correctly.
Is the file uploaded anywhere?
No. The file is read with your browser's file reader and processed on this page only.
Can it save the file back as Shift_JIS?
Not yet. Export is UTF-8 with BOM, which modern Excel and most systems accept.

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