CWK (.cwk)

.cwk file signature | application/x-appleworks

CWK is a legacy document format used by ClarisWorks and later AppleWorks, originally developed by Claris, a division of Apple. It was used for word processing documents and was opened and edited in those desktop office suites on classic Mac OS and Windows systems. The format is largely obsolete, and files from untrusted sources should be handled with care because older documents may not be supported by modern software.

Safe

Magic Bytes

Offset 0


              02 00 5A 57 52 54 00 00 00 00 00 00 00 00 00 00

Sources: Wikipedia

All Known Signatures

6 signature variants are documented for .cwk files across multiple sources.

Hex Signature	Offset	Sources
02 00 5A 57 52 54 00 00 00 00 00 00 00 00 00 00	0	Wikipedia
05 07 00 00 42 4F 42 4F	0	Wikipedia
05 07 00 00 00 00 00 00	0	Wikipedia
00 00 00 00 00 01	0	Wikipedia
06 07 E1 00 42 4F 42 4F	0	Wikipedia
06 07 E1 00 00 00 00 00	0	Wikipedia

Extension

.cwk

MIME Type

application/x-appleworks

Byte Offset

Risk Level

Safe

Validation Code

How to validate .cwk files in Python

Python

def is_cwk(file_path: str) -> bool:
    """Check if file is a valid CWK by magic bytes."""
    signature = bytes([0x02, 0x00, 0x5A, 0x57, 0x52, 0x54, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00])
    with open(file_path, "rb") as f:
        return f.read(16) == signature

How to validate .cwk files in Node.js

Node.js

function isCWK(buffer: Buffer): boolean {
  const signature = Buffer.from([0x02, 0x00, 0x5A, 0x57, 0x52, 0x54, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);
  return buffer.subarray(0, 16).equals(signature);
}

How to validate .cwk files in Go

func IsCWK(data []byte) bool {
    signature := []byte{0x02, 0x00, 0x5A, 0x57, 0x52, 0x54, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
    if len(data) < 16 {
        return false
    }
    return bytes.Equal(data[:16], signature)
}

API Endpoint

GET /api/v1/cwk


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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .cwk file?

A .cwk file is identified by the magic bytes 02 00 5A 57 52 54 00 00 00 00 00 00 00 00 00 00 at byte offset 0. CWK is a legacy document format used by ClarisWorks and later AppleWorks, originally developed by Claris, a division of Apple. It was used for word processing documents and was opened and edited in those desktop office suites on classic Mac OS and Windows systems. The format is largely obsolete, and files from untrusted sources should be handled with care because older documents may not be supported by modern software.

What are the magic bytes for .cwk files?

The magic bytes for CWK files are 02 00 5A 57 52 54 00 00 00 00 00 00 00 00 00 00 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .cwk file?

To validate a .cwk file, read the first bytes of the file and compare them against the known magic bytes (02 00 5A 57 52 54 00 00 00 00 00 00 00 00 00 00) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .cwk files?

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

Is it safe to open .cwk files?

CWK (.cwk) 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.