Open Publication Structure eBook file
application/epub+zip
Magic Bytes
Offset: 0
50 4B 03 04
Open Publication Structure (EPUB) is an open-standard electronic book format developed by the International Digital Publishing Forum and maintained by the World Wide Web Consortium. It is the primary format for digital publications requiring reflowable text to provide consistent readability across various screen sizes and hardware e-readers. While structurally a ZIP archive of XHTML files, security is maintained through sandboxing features like JavaScript and remote resources within modern reading applications.
Validation Code
How to validate .epub files in Python
Python
def is_epub(file_path: str) -> bool:
"""Check if file is a valid EPUB by magic bytes."""
signature = bytes([0x50, 0x4B, 0x03, 0x04])
with open(file_path, "rb") as f:
return f.read(4) == signatureHow to validate .epub files in Node.js
Node.js
function isEPUB(buffer: Buffer): boolean {
const signature = Buffer.from([0x50, 0x4B, 0x03, 0x04]);
return buffer.subarray(0, 4).equals(signature);
}
Go
func IsEPUB(data []byte) bool {
signature := []byte{0x50, 0x4B, 0x03, 0x04}
if len(data) < 4 {
return false
}
return bytes.Equal(data[:4], signature)
}API Endpoint
GET
/api/v1/epub
curl https://filesignature.org/api/v1/epub