FON
application/octet-stream
Magic Bytes
Offset: 0
4D 5A
The FON file format is a legacy font resource library developed by Microsoft for use within the Windows operating system environment. These files primarily function as executable containers storing fixed-size bitmap font data used for system interfaces, dialog boxes, and command prompt windows. Structurally identical to 16-bit Windows executable libraries, this format has largely been superseded by vector-based TrueType and OpenType standards but remains present for backward compatibility.
Validation Code
How to validate .fon files in Python
Python
def is_fon(file_path: str) -> bool:
"""Check if file is a valid FON by magic bytes."""
signature = bytes([0x4D, 0x5A])
with open(file_path, "rb") as f:
return f.read(2) == signatureHow to validate .fon files in Node.js
Node.js
function isFON(buffer: Buffer): boolean {
const signature = Buffer.from([0x4D, 0x5A]);
return buffer.subarray(0, 2).equals(signature);
}
Go
func IsFON(data []byte) bool {
signature := []byte{0x4D, 0x5A}
if len(data) < 2 {
return false
}
return bytes.Equal(data[:2], signature)
}API Endpoint
GET
/api/v1/fon
curl https://filesignature.org/api/v1/fon