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J2K (.j2k)

.j2k file signature | application/octet-stream

JPEG 2000format[18]

Safe

Magic Bytes

Offset 0
00 00 00 0C 6A 50 20 20 0D 0A 87 0A

Sources: Wikipedia

Extension

.j2k

MIME Type

application/octet-stream

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .j2k files in Python

Python 
def is_j2k(file_path: str) -> bool:
    """Check if file is a valid J2K by magic bytes."""
    signature = bytes([0x00, 0x00, 0x00, 0x0C, 0x6A, 0x50, 0x20, 0x20, 0x0D, 0x0A, 0x87, 0x0A])
    with open(file_path, "rb") as f:
        return f.read(12) == signature

How to validate .j2k files in Node.js

Node.js 
function isJ2K(buffer: Buffer): boolean {
  const signature = Buffer.from([0x00, 0x00, 0x00, 0x0C, 0x6A, 0x50, 0x20, 0x20, 0x0D, 0x0A, 0x87, 0x0A]);
  return buffer.subarray(0, 12).equals(signature);
}

How to validate .j2k files in Go

Go 
func IsJ2K(data []byte) bool {
    signature := []byte{0x00, 0x00, 0x00, 0x0C, 0x6A, 0x50, 0x20, 0x20, 0x0D, 0x0A, 0x87, 0x0A}
    if len(data) < 12 {
        return false
    }
    return bytes.Equal(data[:12], signature)
}

API Endpoint

GET /api/v1/j2k
curl https://filesignature.org/api/v1/j2k

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .j2k file?

A .j2k file is a J2K file. JPEG 2000format[18]

What are the magic bytes for .j2k files?

The magic bytes for J2K files are 00 00 00 0C 6A 50 20 20 0D 0A 87 0A at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .j2k file?

To validate a .j2k file, read the first bytes of the file and compare them against the known magic bytes (00 00 00 0C 6A 50 20 20 0D 0A 87 0A) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .j2k files?

There is no officially registered MIME type for .j2k files. Systems typically use application/octet-stream as a generic fallback when handling this format.

Is it safe to open .j2k files?

J2K (.j2k) 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.