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

Name: Byte Order Mark (BOM) Detector
Availability: InStock
Author: Nham Vu

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

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Summary