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Adobe Portable Document Format (.fdf)

.fdf file signature | application/vnd.fdf

Adobe Portable Document Format, Forms Document Format, and Illustrator graphics filesTrailers:0A 25 25 45 4F 46(.%%EOF)0A 25 25 45 4F 46 0A(.%%EOF.)0D 0A 25 25 45 4F 46 0D 0A(..%%EOF..)0D 25 25 45 4F 46 0D(.%%EOF.)NOTE:There may be multiple end-of-file marks within thefile. When carving, be sure to get the last one.

Safe

Magic Bytes

Offset 0
25 46 44 46 2D

Sources: Apache Tika

All Known Signatures

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

Hex Signature Offset Sources
25 46 44 46 2D 0 Apache Tika
25 50 44 46 0 Gary Kessler

Extension

.fdf

MIME Type

application/vnd.fdf

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .fdf files in Python

Python 
def is_fdf(file_path: str) -> bool:
    """Check if file is a valid FDF by magic bytes."""
    signature = bytes([0x25, 0x46, 0x44, 0x46, 0x2D])
    with open(file_path, "rb") as f:
        return f.read(5) == signature

How to validate .fdf files in Node.js

Node.js 
function isFDF(buffer: Buffer): boolean {
  const signature = Buffer.from([0x25, 0x46, 0x44, 0x46, 0x2D]);
  return buffer.subarray(0, 5).equals(signature);
}

How to validate .fdf files in Go

Go 
func IsFDF(data []byte) bool {
    signature := []byte{0x25, 0x46, 0x44, 0x46, 0x2D}
    if len(data) < 5 {
        return false
    }
    return bytes.Equal(data[:5], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .fdf file?

A .fdf file is a Adobe Portable Document Format file. Adobe Portable Document Format, Forms Document Format, and Illustrator graphics filesTrailers:0A 25 25 45 4F 46(.%%EOF)0A 25 25 45 4F 46 0A(.%%EOF.)0D 0A 25 25 45 4F 46 0D 0A(..%%EOF..)0D 25 25 45 4F 46 0D(.%%EOF.)NOTE:There may be multiple end-of-file marks within thefile. When carving, be sure to get the last one.

What are the magic bytes for .fdf files?

The magic bytes for Adobe Portable Document Format files are 25 46 44 46 2D at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .fdf file?

To validate a .fdf file, read the first bytes of the file and compare them against the known magic bytes (25 46 44 46 2D) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .fdf files?

The primary MIME type for .fdf files is application/vnd.fdf.

Is it safe to open .fdf files?

Adobe Portable Document Format (.fdf) 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.