CDF (.cdf)

.cdf file signature | application/x-netcdf

Safe

Magic Bytes

Offset 0


              43 44 46 01

Sources: Apache Tika

All Known Signatures

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

Hex Signature	Offset	Sources
43 44 46 01	0	Apache Tika
43 44 46 02	0	Apache Tika

Extension

.cdf

MIME Type

application/x-netcdf

Byte Offset

Risk Level

Safe

Validation Code

How to validate .cdf files in Python

Python

def is_cdf(file_path: str) -> bool:
    """Check if file is a valid CDF by magic bytes."""
    signature = bytes([0x43, 0x44, 0x46, 0x01])
    with open(file_path, "rb") as f:
        return f.read(4) == signature

How to validate .cdf files in Node.js

Node.js

function isCDF(buffer: Buffer): boolean {
  const signature = Buffer.from([0x43, 0x44, 0x46, 0x01]);
  return buffer.subarray(0, 4).equals(signature);
}

How to validate .cdf files in Go

func IsCDF(data []byte) bool {
    signature := []byte{0x43, 0x44, 0x46, 0x01}
    if len(data) < 4 {
        return false
    }
    return bytes.Equal(data[:4], signature)
}

API Endpoint

GET /api/v1/cdf


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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .cdf file?

A .cdf file is a CDF file.

What are the magic bytes for .cdf files?

The magic bytes for CDF files are 43 44 46 01 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .cdf file?

To validate a .cdf file, read the first bytes of the file and compare them against the known magic bytes (43 44 46 01) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .cdf files?

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

Is it safe to open .cdf files?

CDF (.cdf) 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.