CDX (.cdx)

.cdx file signature | chemical/x-cdx

CDX is the binary ChemDraw exchange format developed by CambridgeSoft and maintained through ChemDraw and related chemistry software from PerkinElmer and its successors. It is used to store and share chemical structures, reactions, annotations, and laboratory drawings in documents and scientific workflows. The format is generally safe, but older or third-party parsers may have compatibility issues, and legacy files may not render correctly in modern applications.

Safe

Magic Bytes

Offset 0


              56 6A 43 44 30 31 30 30

Sources: Apache Tika

All Known Signatures

2 signature variants are documented for .cdx files across multiple sources.

Hex Signature	Offset	Sources
56 6A 43 44 30 31 30 30	0	Apache Tika
41 72 43	0	Wikipedia

Extension

.cdx

MIME Type

chemical/x-cdx

Byte Offset

Risk Level

Safe

Validation Code

How to validate .cdx files in Python

Python

def is_cdx(file_path: str) -> bool:
    """Check if file is a valid CDX by magic bytes."""
    signature = bytes([0x56, 0x6A, 0x43, 0x44, 0x30, 0x31, 0x30, 0x30])
    with open(file_path, "rb") as f:
        return f.read(8) == signature

How to validate .cdx files in Node.js

Node.js

function isCDX(buffer: Buffer): boolean {
  const signature = Buffer.from([0x56, 0x6A, 0x43, 0x44, 0x30, 0x31, 0x30, 0x30]);
  return buffer.subarray(0, 8).equals(signature);
}

How to validate .cdx files in Go

func IsCDX(data []byte) bool {
    signature := []byte{0x56, 0x6A, 0x43, 0x44, 0x30, 0x31, 0x30, 0x30}
    if len(data) < 8 {
        return false
    }
    return bytes.Equal(data[:8], signature)
}

API Endpoint

GET /api/v1/cdx


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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .cdx file?

A .cdx file is identified by the magic bytes 56 6A 43 44 30 31 30 30 at byte offset 0. CDX is the binary ChemDraw exchange format developed by CambridgeSoft and maintained through ChemDraw and related chemistry software from PerkinElmer and its successors. It is used to store and share chemical structures, reactions, annotations, and laboratory drawings in documents and scientific workflows. The format is generally safe, but older or third-party parsers may have compatibility issues, and legacy files may not render correctly in modern applications.

What are the magic bytes for .cdx files?

The magic bytes for CDX files are 56 6A 43 44 30 31 30 30 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .cdx file?

To validate a .cdx file, read the first bytes of the file and compare them against the known magic bytes (56 6A 43 44 30 31 30 30) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .cdx files?

The primary MIME type for .cdx files is chemical/x-cdx.

Is it safe to open .cdx files?

CDX (.cdx) 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.