What is a Byte Order Mark?

A BOM is the Unicode character U+FEFF placed at the start of a text stream. It was originally used to indicate byte order for UTF-16/UTF-32 files. In UTF-8 files a BOM is optional and often causes problems because many parsers are not designed to skip it.

What does a UTF-8 BOM look like in hex?

The UTF-8 BOM is three bytes: EF BB BF. UTF-16 LE is FF FE, UTF-16 BE is FE FF, UTF-32 LE is FF FE 00 00, and UTF-32 BE is 00 00 FE FF.

Why does a BOM break my code?

Languages like PHP, Python, and many JSON/CSV parsers read input byte by byte. If the very first bytes are an unexpected BOM, the parser may throw a syntax error, return an empty first field, or produce garbled output before it reads any real content.

Does this tool send my text to a server?

No. All detection and stripping happens entirely in your browser using JavaScript. Your text is never transmitted anywhere.

Can I detect a BOM in a binary file?

This tool works with text you can paste into a browser. For binary files, use a hex editor or a command-line tool such as `file` or `hexdump`.

Should I always remove BOMs?

For UTF-8 files it is generally best to omit the BOM. For UTF-16 and UTF-32 files, the BOM is part of the standard and typically required to identify byte order correctly.

Byte Order Mark (BOM) Detector

Paste text to instantly detect whether it contains a Byte Order Mark, see the BOM bytes in hex, and copy a clean BOM-free version.

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Known BOM Signatures

Encoding	Hex Bytes	Length
UTF-8	EF BB BF	3 bytes
UTF-16 LE	FF FE	2 bytes
UTF-16 BE	FE FF	2 bytes
UTF-32 LE	FF FE 00 00	4 bytes
UTF-32 BE	00 00 FE FF	4 bytes

Detection Result

Paste text on the left to analyze

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Summary

A Byte Order Mark (BOM) is a special Unicode character (U+FEFF) placed at the very beginning of a text file to signal its encoding and byte order. While useful in some contexts, unexpected BOMs — especially the UTF-8 BOM — cause parsing errors, broken CSV imports, and garbled output in many programming environments. This tool lets you paste any text, instantly detects the presence and type of BOM, shows the raw hex bytes, and gives you a clean BOM-free copy.

How it works

Paste or type your text into the input area.
The tool reads the first 4 bytes of the text to identify known BOM signatures.
If a BOM is found, the encoding type and hex bytes are displayed.
View the automatically stripped BOM-free text in the output panel.
Copy the result to clipboard with one click.

Use cases

Debug broken CSV or JSON files caused by a stray UTF-8 BOM.
Verify that source code files do not carry an unexpected BOM.
Check text copied from Windows Notepad or Microsoft Word.
Confirm encoding before uploading data to a database or API.
Strip the BOM from configuration files that break parser tools.
Inspect clipboard content when a script fails on the first byte.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu