日本語English

CSV Encoding Fix

Convert CSV files that show garbled text in Excel to UTF-8 with BOM or Shift_JIS, with automatic encoding detection. Mojibake that was already saved, such as “日本語”, can usually be restored too.

On-device・No upload

Your files and input are processed only inside your browser on this device and are never uploaded to our servers.

Drop files here (multiple allowed)

or

Accepts: CSV / TSV / TXTUp to 100 MB per filePaste (Ctrl+V) also works

How to use

  1. Drop garbled CSV, TSV or TXT files, or click “Choose files” (several at once is fine).

  2. Check the detected encoding and the converted preview. If the text is still unreadable, pick the candidate under “Read the file as” whose text reads correctly.

  3. Choose the encoding to save as. For Excel, “UTF-8 with BOM” or “Shift_JIS” open reliably. Change line endings if needed.

  4. Garbled text such as “縺薙ｓ…” or “æ—¥…” is repaired automatically. Highlighted lines were repaired or changed.

  5. Download the file, or all files as a ZIP.

What it does

Automatic detection, with candidates to compare

Combines BOM, UTF-8 validity and how natural the decoded text looks. For tricky files, the first lines of each candidate are shown side by side so you can click the one that reads correctly.

Restores saved mojibake

Recognises three common patterns — UTF-8 opened as Shift_JIS and saved (縺薙ｓ縺ｫ縺｡縺ｯ), UTF-8 read as Western/Windows-1252 (日本語) and Shift_JIS read as Western (ƒeƒXƒg) — and restores them line by line. Characters already lost are shown as “�”.

Warns about characters the target cannot hold

When converting to Shift_JIS, emoji and other unsupported characters are listed with their line numbers, so nothing silently turns into “?”.

Converts without touching content

The CSV is not re-parsed as a table, so quotes, delimiters and in-cell line breaks are kept. Only the encoding, chosen line endings and repaired/normalised characters change.

Line endings and Unicode normalisation

Unify to CRLF (Windows) or LF (Mac/Linux), and join detached dakuten marks common in Mac files (Unicode NFC).

Use cases

  • A UTF-8 CSV exported from a system shows garbled text in Excel
  • Import a Shift_JIS CSV saved by Excel into a web service or Google Sheets (which expect UTF-8)
  • Restore a CSV that was saved after it had already been garbled
  • Japanese characters made on a Mac show detached dakuten marks (“か゛”)
  • Unify the encoding and line endings of many CSV files at once

Supported formats

Input

CSV / TSV / TXT and other text filesUTF-8 (with or without BOM)Shift_JIS (CP932)EUC-JPUTF-16 LE / BEISO-2022-JP

Output

UTF-8 with BOMUTF-8Shift_JIS (CP932)EUC-JPUTF-16 LE (with BOM)ZIP (multiple files)

Capability matrix

FeatureSupportNotes
Automatic or manual source encodingSupported—
Convert to UTF-8 (BOM), Shift_JIS, EUC-JP, UTF-16Supported—
Restore saved mojibake (縺薙ｓ, æ—¥, ƒeƒX)PartialCharacters lost at garbling time cannot return
Line-ending conversion, NFC normalisationSupported—
Batch conversion with ZIP downloadSupported—
Restore characters saved as “?” or “・”Not supportedThe original data no longer exists
Excel files (.xlsx)Not supportedSave as CSV with “Excel Cleanup”

Limits & notes

  • Up to 100 MB per file. The preview shows the first 200 lines (conversion applies to the whole file).
  • Mojibake repair covers three typical patterns. Text garbled several times, or saved with “?”/“・” substitutions, cannot be restored.
  • Detection uses the first 256 KB. For files that switch encoding part-way, choose the encoding that reads correctly yourself.

Privacy & safety

Reading, detection and conversion all happen in your browser. Your files are never sent to or stored on a server.

FAQ

Why does my CSV look garbled in Excel?
Japanese Excel reads CSV files without a BOM as Shift_JIS, and other locales use their own legacy encoding, so a UTF-8 CSV shows mojibake. Converting it to “UTF-8 with BOM” makes Excel open it correctly with a double-click.
Can text like “日本語” be fixed?
Usually yes. It is UTF-8 text that was read as Windows-1252 and saved. The tool detects it and restores the original characters automatically.
Should I save as Shift_JIS or UTF-8?
Both open correctly in Japanese Excel on Windows. Choose UTF-8 with BOM if the data has emoji or characters outside Shift_JIS, or if it goes into a web service or Google Sheets.
What is a BOM?
A 3-byte marker at the start of a file saying “this is UTF-8”. Excel uses it to open CSV files as UTF-8. Some programs expect no BOM — choose plain “UTF-8” for those.
Are my files uploaded?
No. Everything runs in your browser and your files never leave your device.

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Excel Compare

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