ISO-9660 CD Disc ImageThis signature usually occurs at byte offset 32769 (.iso)
.iso file signature | application/x-iso9660-image
ISO 9660 is a standard optical disc file system jointly defined by the International Organization for Standardization (ISO) and ECMA International. It is used for CD-ROM and DVD images, software distribution, archival copies, and bootable installation media across many operating systems. The format is long established and generally safe, though some legacy images may reflect the limitations of older media and filesystem conventions.
Magic Bytes
Offset 0
43 44 30 30 31
Sources: Wikipedia, Gary Kessler
All Known Signatures
6 signature variants are documented for .iso files across multiple sources.
| Hex Signature | Offset | Sources |
|---|---|---|
| 43 44 30 30 31 | 0 | Wikipedia, Gary Kessler |
| 43 44 30 30 31 | 32769 | Apache Tika |
| 43 44 30 30 31 | 34817 | Apache Tika |
| 43 44 30 30 31 | 36865 | Apache Tika |
| 45 4D 55 33 | 0 | Wikipedia |
| 45 52 02 00 00 | 0 | Gary Kessler |
Extension
.iso
MIME Type
application/x-iso9660-image
Byte Offset
0
Risk Level
Safe
Validation Code
How to validate .iso files in Python
def is_iso(file_path: str) -> bool:
"""Check if file is a valid ISO by magic bytes."""
signature = bytes([0x43, 0x44, 0x30, 0x30, 0x31])
with open(file_path, "rb") as f:
return f.read(5) == signatureHow to validate .iso files in Node.js
function isISO(buffer: Buffer): boolean {
const signature = Buffer.from([0x43, 0x44, 0x30, 0x30, 0x31]);
return buffer.subarray(0, 5).equals(signature);
}How to validate .iso files in Go
func IsISO(data []byte) bool {
signature := []byte{0x43, 0x44, 0x30, 0x30, 0x31}
if len(data) < 5 {
return false
}
return bytes.Equal(data[:5], signature)
}API Endpoint
/api/v1/iso
curl https://filesignature.org/api/v1/iso
See the full API documentation for all endpoints and parameters.
Related Formats
Frequently Asked Questions
What is a .iso file?
A .iso file is a ISO-9660 CD Disc ImageThis signature usually occurs at byte offset 32769 file. ISO 9660 is a standard optical disc file system jointly defined by the International Organization for Standardization (ISO) and ECMA International. It is used for CD-ROM and DVD images, software distribution, archival copies, and bootable installation media across many operating systems. The format is long established and generally safe, though some legacy images may reflect the limitations of older media and filesystem conventions.
What are the magic bytes for .iso files?
The magic bytes for ISO-9660 CD Disc ImageThis signature usually occurs at byte offset 32769 files are 43 44 30 30 31 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.
How do I validate a .iso file?
To validate a .iso file, read the first bytes of the file and compare them against the known magic bytes (43 44 30 30 31) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.
What is the MIME type for .iso files?
The primary MIME type for .iso files is application/x-iso9660-image.
Is it safe to open .iso files?
ISO-9660 CD Disc ImageThis signature usually occurs at byte offset 32769 (.iso) 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.