Adobe Portable Document Format (.pdf)
.pdf file signature | application/pdf
Portable Document Format (PDF) is a file format created by Adobe Systems and now maintained as an open standard by ISO for representing documents independently of software and hardware. It is used for distributing reports, forms, manuals, books, and other fixed-layout documents across desktop and mobile applications. PDFs can include embedded media, scripts, and links, so files from untrusted sources should be opened with current readers and security features enabled.
Magic Bytes
Offset 0
25 50 44 46 2D
Sources: Apache Tika, Wikipedia
All Known Signatures
6 signature variants are documented for .pdf files across multiple sources.
| Hex Signature | Offset | Sources |
|---|---|---|
| 25 50 44 46 2D | 0 | Apache Tika, Wikipedia |
| 25 50 44 46 | 0 | Gary Kessler, Neil Harvey FileSignatures |
| EF BB BF 25 50 44 46 2D | 0 | Apache Tika |
| 25 25 | 0 | Apache Tika |
| 25 50 44 46 2D 31 2E | 1 | Apache Tika |
| 25 50 44 46 2D 32 2E | 1 | Apache Tika |
Extension
MIME Type
application/pdf
Byte Offset
0
Risk Level
Safe
Validation Code
How to validate .pdf files in Python
def is_pdf(file_path: str) -> bool:
"""Check if file is a valid PDF by magic bytes."""
signature = bytes([0x25, 0x50, 0x44, 0x46, 0x2D])
with open(file_path, "rb") as f:
return f.read(5) == signatureHow to validate .pdf files in Node.js
function isPDF(buffer: Buffer): boolean {
const signature = Buffer.from([0x25, 0x50, 0x44, 0x46, 0x2D]);
return buffer.subarray(0, 5).equals(signature);
}How to validate .pdf files in Go
func IsPDF(data []byte) bool {
signature := []byte{0x25, 0x50, 0x44, 0x46, 0x2D}
if len(data) < 5 {
return false
}
return bytes.Equal(data[:5], signature)
}API Endpoint
/api/v1/pdf
curl https://filesignature.org/api/v1/pdf
See the full API documentation for all endpoints and parameters.
Related Formats
Frequently Asked Questions
What is a .pdf file?
A .pdf file is a Adobe Portable Document Format file. Portable Document Format (PDF) is a file format created by Adobe Systems and now maintained as an open standard by ISO for representing documents independently of software and hardware. It is used for distributing reports, forms, manuals, books, and other fixed-layout documents across desktop and mobile applications. PDFs can include embedded media, scripts, and links, so files from untrusted sources should be opened with current readers and security features enabled.
What are the magic bytes for .pdf files?
The magic bytes for Adobe Portable Document Format files are 25 50 44 46 2D at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.
How do I validate a .pdf file?
To validate a .pdf file, read the first bytes of the file and compare them against the known magic bytes (25 50 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 .pdf files?
The primary MIME type for .pdf files is application/pdf.
Is it safe to open .pdf files?
Adobe Portable Document Format (.pdf) 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.