CSV characters are garbled in Excel. What should I do?

Please turn on 'Add UTF-8 BOM' and download. If the Windows version of Excel does not have a BOM, it will interpret it as Shift_JIS, so characters will be garbled.

When loading a Shift_JIS (CP932) CSV, characters are garbled

Please change the 'Input Encoding' to 'Shift_JIS (CP932)'. This tool generates output in UTF-8, but you can choose the input character encoding.

Is the data sent to the server?

No. The entire process of reading, converting, and downloading files is completed within the browser.

📊

csv-bom-newline,

CSV garbled characters prevention tool
(BOM addition/line feed code conversion)

Solve the problem of garbled CSV characters and broken line breaks in Excel with one click.
UTF-8 Executes BOM addition/deletion, line feed code conversion (LF/CRLF), and end-of-line blank deletion.

⚡️

In-Browser Processing

No data is sent to any server

✨️

No Registration

No account needed — use immediately

🛡️

Auto-Convert

Instant preview on option change

CSV (Input)

📂 Drag & drop a CSV file here

CSV / TSV / TXT — processed in browser

Input Encoding (File Upload)

CSV files saved in Excel may use Shift_JIS (CP932).

Output Filename (optional)

If a source file exists, the base name is inherited automatically.

Paste Text (CSV content)

* Content is processed in your browser and never sent to a server.

Conversion Options

Add UTF-8 BOM Remove leading BOM

Newline Code

Trim trailing whitespace Add newline at end of file Auto-update

If both 'Add BOM' and 'Remove BOM' are on, BOM is first removed then added (resulting in exactly one BOM at the start).

about,

About

When opening a CSV file in Excel, Japanese characters are garbled and line breaks are broken - this is a tool that solves such problems with one click. You can instantly add/delete UTF-8 BOM (Byte Order Mark) and convert line feed codes (LF/CRLF) on your browser.

Also supports loading CSV files saved in Shift_JIS (CP932). Automatically detects the input character code and processes it using the optimal method.すべての処理はブラウ��内で完結し、データが外部サーバーに送信されることはありません。

how to use,

How to Use

STEP 1

Load CSV file

Drag and drop the file or click the "Select File" button. You can also paste text directly. Please switch the input character code for Shift_JIS files.

STEP 2

Set conversion options

Select options according to your purpose, such as "Add UTF-8 BOM" or "Unify new line code to CRLF". If "Automatic Update" is ON, the results will be reflected immediately.

STEP 3

Copy or download result

Copy the conversion result to your clipboard or download it as a CSV file. The file name is automatically generated from the original file.

glossary,

Glossary

CSV (Comma Separated Values): A plain text file format that uses commas to separate values. A standard for data exchange between spreadsheets and databases.
BOM (Byte Order Mark): An invisible marker at the beginning of a text file indicating it is encoded in UTF-8. Without it, Microsoft Excel often scrambles UTF-8 characters.
Line Endings (CR / LF): Invisible characters signifying the end of a line. Windows uses CRLF (Carriage Return + Line Feed) while Unix/Linux/Mac use LF only. Mismatches cause import errors.
Mojibake (Scrambled Text): The phenomenon where characters are displayed incorrectly (as random symbols) because the software is interpreting the file with the wrong character encoding.
UTF-8: The dominant character encoding for the web. While developers prefer UTF-8 "without BOM", business users need UTF-8 "with BOM" so Excel opens it automatically.
Blob API: An HTML5 feature used by this tool to manipulate file binary data entirely within the browser memory, preventing the need for server uploads.
Batch Processing: The capability to process multiple files simultaneously. You can drag and drop 10 files, and the tool outputs them zipped with consistent encoding.

faq,

FAQ

Q.Are my CSV files uploaded to your servers?: No, they never leave your device. All reading, byte manipulation, and file compiling is done securely within your local web browser.
Q.Why do foreign characters look weird when I open a CSV in Excel?: Excel defaults to local Windows encodings unless it explicitly sees a BOM. Use this tool to "Add BOM" and your characters will display perfectly.
Q.Why did my database import fail with a "newline error"?: Many web databases (like MySQL/Postgres on Linux) expect LF line endings. If you saved it on Windows (CRLF), you need to select "Convert to LF" here before importing.
Q.How large of a file can this handle?: It comfortably handles multi-megabyte files (up to ~50MB) almost instantly. Extremely large files (100MB+) may crash the browser tab due to client-side memory limits.
Q.Can I fix multiple files at the same time?: Yes. Simply drag your entire folder of CSVs into the drop zone. It will apply your BOM and newline rules to all of them and package them into a neat ZIP file.
Q.Does this convert Windows-1252 or Shift-JIS to UTF-8?: No. This tool specifically manages BOM signatures and Newline characters for text that is already UTF-8. Legacy encodings should be converted to UTF-8 first.
Q.Will this overwrite my original files?: No. The processed files are returned to you as downloads. Your original source files remain completely untouched on your hard drive.