Fix Garbled CSV Files (Excel)
A CSV that opens as "譁?蟄怜喧" or "�" in Excel almost always has an encoding mismatch. Load the file, let the tool detect its encoding, and download a version Excel opens correctly. Nothing is uploaded.
Why Excel garbles CSV files
When you double-click a CSV, Excel on Windows assumes the legacy system codepage (Shift_JIS in Japan) unless the file starts with a BOM. Most modern systems export UTF-8, and that mismatch is the whole problem. Adding the three-byte UTF-8 BOM (EF BB BF) usually fixes it outright.
Reading the mojibake tells you the cause
Latin gibberish like "テスト" means UTF-8 was read as Latin-1. Unrelated kanji means UTF-8 was read as Shift_JIS. A row of "?" means the data was already destroyed during an earlier conversion.
Which output to choose
Pick UTF-8 with BOM when the file is for Excel — it is the only choice that also preserves emoji and non-Japanese scripts. Pick Shift_JIS when a legacy accounting or line-of-business system needs it, accepting that unsupported characters become "?".
Frequently asked questions
How do I fix a CSV that is garbled in Excel?
Load it here, choose "UTF-8 with BOM" as the output, convert and download. The downloaded file opens correctly on a double-click.
What is UTF-8 with BOM?
Ordinary UTF-8 with a three-byte marker (EF BB BF) at the start. Excel uses that marker to recognise the encoding, and other software reads the file normally.
Can an already-garbled file be repaired?
Yes, as long as the original bytes are intact — that is the case when the file merely looks wrong on screen. If it was re-saved from Excel while garbled, information is gone and full recovery is impossible.
Does the CSV content change?
Only the encoding changes. Delimiters, quoting and cell contents — including quoted cells with embedded line breaks — are preserved byte for byte.