Free Developer Tool
BOM Detector
Detect and identify Unicode byte order marks such as UTF-8, UTF-16 and UTF-32 BOMs in text data.
Only the first 16 bytes are inspected. The file is processed locally in your browser and is not uploaded to a server.
Common BOM Signatures
| Encoding | Type | Bytes | Length |
|---|---|---|---|
| UTF-8 | BOM | EF BB BF | 3 bytes |
| UTF-32 LE | BOM | FF FE 00 00 | 4 bytes |
| UTF-32 BE | BOM | 00 00 FE FF | 4 bytes |
| UTF-16 LE | BOM | FF FE | 2 bytes |
| UTF-16 BE | BOM | FE FF | 2 bytes |
| UTF-7 | Encoding signature | 2B 2F 76 38 2D | 5 bytes |
| UTF-7 | Encoding signature | 2B 2F 76 38 | 4 bytes |
| UTF-7 | Encoding signature | 2B 2F 76 39 | 4 bytes |
| UTF-7 | Encoding signature | 2B 2F 76 2B | 4 bytes |
| UTF-7 | Encoding signature | 2B 2F 76 2F | 4 bytes |
| UTF-1 | Encoding signature | F7 64 4C | 3 bytes |
| UTF-EBCDIC | Encoding signature | DD 73 66 73 | 4 bytes |
| SCSU | Encoding signature | 0E FE FF | 3 bytes |
| BOCU-1 | Encoding signature | FB EE 28 | 3 bytes |
| GB-18030 | BOM | 84 31 95 33 | 4 bytes |
Notes
• BOM stands for Byte Order Mark.
• A BOM or encoding signature is located at the beginning of a byte stream.
• UTF-8 does not require a BOM, although EF BB BF may be present.
• UTF-16 and UTF-32 BOMs can indicate byte order.
• Some encodings, such as UTF-7, use an encoding signature rather than a conventional BOM.
• A missing BOM does not mean that a file is invalid or that its encoding cannot be determined.
• The detector examines the actual file bytes and does not decode the file as text first.
• Only the beginning of the file is read, so large files can be checked efficiently.
• Everything is processed locally in the browser.
What is BOM Detector?
Upload a file to detect a byte order mark (BOM) at the beginning of its binary data and identify the corresponding encoding signature.
How to use
- Select a file to inspect.
- The tool reads the first few bytes of the file.
- Check whether a recognized BOM signature is present.
- Review the detected BOM type, byte signature, and length.
Features
- BOM detection
- UTF-8 BOM identification
- UTF-16 BOM identification
- UTF-32 BOM identification
- Additional Unicode encoding signatures
- Raw byte inspection
Common Use Cases
- Encoding troubleshooting
- File inspection
- Unicode debugging
- Data import issues
- Text file analysis
Example
Input
A text file beginning with the UTF-8 BOM bytes EF BB BF.
Output
BOM: UTF-8 Signature: EF BB BF Length: 3 bytes BOM detected
FAQ
Does the tool inspect the actual file bytes?
Yes. It reads the beginning of the selected file as raw bytes instead of decoding the file as text first.
Can it detect UTF-8, UTF-16, and UTF-32 BOMs?
Yes. It recognizes UTF-8, UTF-16 LE/BE, UTF-32 LE/BE, and several additional encoding signatures.
Does the tool upload or modify my file?
No. Only the beginning of the selected file is read locally in the browser, and the original file is not modified or uploaded.
Missing a feature?
If this tool doesn't cover your use case or is missing functionality, please let me know through the Contact page.
New improvements and features are added based on user feedback.