ZOO compressed archive (.zoo)

.zoo file signature | application/x-zoo

ZOO compressed archive is a legacy archive format created by Rahul Dhesi and preserved today mainly by the archival community. It was used to compress and bundle files for transfer, backup, and distribution on early MS-DOS and Unix systems. Because it is an older format, support in modern software is limited, and files from untrusted sources should be handled with standard caution, as with any archived content.

Safe

Magic Bytes

Offset 20


              FD C4 A7 DC

Sources: Apache Tika

All Known Signatures

3 signature variants are documented for .zoo files across multiple sources.

Hex Signature	Offset	Sources
FD C4 A7 DC	20	Apache Tika
5A 4F 4F	0	Wikipedia
5A 4F 4F 20	0	Gary Kessler

Extension

.zoo

MIME Type

application/x-zoo

Byte Offset

Risk Level

Safe

Validation Code

How to validate .zoo files in Python

Python

def is_zoo(file_path: str) -> bool:
    """Check if file is a valid ZOO by magic bytes at offset 20."""
    signature = bytes([0xFD, 0xC4, 0xA7, 0xDC])
    with open(file_path, "rb") as f:
        f.seek(20)
        return f.read(4) == signature

How to validate .zoo files in Node.js

Node.js

function isZOO(buffer: Buffer): boolean {
  const signature = Buffer.from([0xFD, 0xC4, 0xA7, 0xDC]);
  if (buffer.length < 24) return false;
  return buffer.subarray(20, 24).equals(signature);
}

How to validate .zoo files in Go

func IsZOO(data []byte) bool {
    signature := []byte{0xFD, 0xC4, 0xA7, 0xDC}
    if len(data) < 24 {
        return false
    }
    return bytes.Equal(data[20:24], signature)
}

API Endpoint

GET /api/v1/zoo


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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .zoo file?

A .zoo file is a ZOO compressed archive file. ZOO compressed archive is a legacy archive format created by Rahul Dhesi and preserved today mainly by the archival community. It was used to compress and bundle files for transfer, backup, and distribution on early MS-DOS and Unix systems. Because it is an older format, support in modern software is limited, and files from untrusted sources should be handled with standard caution, as with any archived content.

What are the magic bytes for .zoo files?

The magic bytes for ZOO compressed archive files are FD C4 A7 DC at byte offset 20. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .zoo file?

To validate a .zoo file, read the first bytes of the file and compare them against the known magic bytes (FD C4 A7 DC) at offset 20. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .zoo files?

The primary MIME type for .zoo files is application/x-zoo.

Is it safe to open .zoo files?

ZOO compressed archive (.zoo) 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.