ISO-9660 CD Disc ImageThis signature usually occurs at byte offset 32769 (.iso)

.iso file signature | application/x-iso9660-image

ISO-9660 CD Disc ImageThis signature usually occurs at byte offset 32769 (0x8001),34817 (0x8801), or 36865 (0x9001).More information can be found atMacTechor atECMA.

Safe

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

Risk Level

Safe

Validation Code

How to validate .iso files in Python

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) == signature

How to validate .iso files in Node.js

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

GET /api/v1/iso


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

See the full API documentation for all endpoints and parameters.

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 CD Disc ImageThis signature usually occurs at byte offset 32769 (0x8001),34817 (0x8801), or 36865 (0x9001).More information can be found atMacTechor atECMA.

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.