FAX (.fax)

.fax file signature | application/octet-stream

IFFFacsimile Image

Safe

Magic Bytes

Offset 0


              46 4F 52 4D 46 41 58 58

Sources: Wikipedia

Extension

.fax

MIME Type

application/octet-stream

Byte Offset

Risk Level

Safe

Validation Code

How to validate .fax files in Python

Python

def is_fax(file_path: str) -> bool:
    """Check if file is a valid FAX by magic bytes."""
    signature = bytes([0x46, 0x4F, 0x52, 0x4D, 0x46, 0x41, 0x58, 0x58])
    with open(file_path, "rb") as f:
        return f.read(8) == signature

How to validate .fax files in Node.js

Node.js

function isFAX(buffer: Buffer): boolean {
  const signature = Buffer.from([0x46, 0x4F, 0x52, 0x4D, 0x46, 0x41, 0x58, 0x58]);
  return buffer.subarray(0, 8).equals(signature);
}

How to validate .fax files in Go

func IsFAX(data []byte) bool {
    signature := []byte{0x46, 0x4F, 0x52, 0x4D, 0x46, 0x41, 0x58, 0x58}
    if len(data) < 8 {
        return false
    }
    return bytes.Equal(data[:8], signature)
}

API Endpoint

GET /api/v1/fax


              curl https://filesignature.org/api/v1/fax

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .fax file?

A .fax file is a FAX file. IFFFacsimile Image

What are the magic bytes for .fax files?

The magic bytes for FAX files are 46 4F 52 4D 46 41 58 58 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .fax file?

To validate a .fax file, read the first bytes of the file and compare them against the known magic bytes (46 4F 52 4D 46 41 58 58) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .fax files?

There is no officially registered MIME type for .fax files. Systems typically use application/octet-stream as a generic fallback when handling this format.

Is it safe to open .fax files?

FAX (.fax) files are generally safe to open. They are classified as low risk because they primarily contain data rather than executable code. However, always ensure files come from a trusted source.