Document
Word Open XML Document is a document format commonly identified by .docx. Use the listed signatures, MIME types, and structure notes to validate files beyond the extension.
50 4B 03 04 PK..SIGNATURE = bytes.fromhex("504b0304")
OFFSET = 0
def is_docx(path: str) -> bool:
with open(path, "rb") as f:
f.seek(OFFSET)
head = f.read(len(SIGNATURE))
return head == SIGNATUREconst SIGNATURE = [0x50, 0x4b, 0x03, 0x04];
const OFFSET = 0;
// bytes: a Uint8Array / Buffer holding the start of the file
export function isDocx(bytes) {
return SIGNATURE.every((byte, i) => bytes[OFFSET + i] === byte);
}package fileid
import "bytes"
var isdocxSignature = []byte{0x50, 0x4b, 0x03, 0x04}
const isdocxOffset = 0
func IsDocx(b []byte) bool {
end := isdocxOffset + len(isdocxSignature)
if len(b) < end {
return false
}
return bytes.Equal(b[isdocxOffset:end], isdocxSignature)
}const SIGNATURE: &[u8] = &[0x50, 0x4b, 0x03, 0x04];
const OFFSET: usize = 0;
fn is_docx(bytes: &[u8]) -> bool {
bytes.get(OFFSET..OFFSET + SIGNATURE.len()) == Some(SIGNATURE)
}<?php
$signature = "\x50\x4b\x03\x04";
$offset = 0;
function is_docx(string $bytes): bool {
global $signature, $offset;
return substr($bytes, $offset, strlen($signature)) === $signature;
}Word Open XML Document is used for data exchange, imports, exports, parser testing, and validation workflows. Encoding, delimiters, versions, and container structure often change implementation behavior.
Document formats may include scripts, attachments, macros, or external references. Sandbox previews and conversions, and avoid opening untrusted files directly.
11 samples help test leading-byte detection, parser errors, upload limits, and download behavior.
Blue Sky DOCX is a Word Open XML Document sample based on Wikimedia Commons. It can be used to test downloads, parsers, previews, and file type detection.
01-blue-sky.docxecdeb8876f29896e26ab2291c275b7dda500eb769669fbdaa5b3e16123eb7bb0Flower Garden DOCX is a Word Open XML Document sample based on Wikimedia Commons. It can be used to test downloads, parsers, previews, and file type detection.
02-flower-garden.docxaa9203da7c21b43c532ac66622a34ce7952efbc62fb49cab0cf7d53f685c276dNavy Blue Sky DOCX is a Word Open XML Document sample based on Wikimedia Commons. It can be used to test downloads, parsers, previews, and file type detection.
03-navy-blue-sky.docx165ba457ca04d0963c0f8779cc1aafb8eca9dd87a5c996d1c0a62e6f845248feNature of the Sky DOCX is a Word Open XML Document sample based on Wikimedia Commons. It can be used to test downloads, parsers, previews, and file type detection.
04-nature-sky.docx8a5ba5754bee861941c74d490604a26e53a156097574b4492fbd62e20c40e8b6Sky Landscape DOCX is a Word Open XML Document sample based on Wikimedia Commons. It can be used to test downloads, parsers, previews, and file type detection.
05-sky-landscape.docxcb45942888fa84fe6c1f5d06023f317dcee8a0271ba333947a1da78aef77b1bfStarry Sky DOCX is a Word Open XML Document sample based on Wikimedia Commons. It can be used to test downloads, parsers, previews, and file type detection.
06-starry-sky.docxfebd4887b583dfc0ab0f253fb2056ec0f6a16e7fc44f616ba35d926e0185c89bBlue Night Sky DOCX is a Word Open XML Document sample based on Wikimedia Commons. It can be used to test downloads, parsers, previews, and file type detection.
07-blue-night-sky.docx1663e4dc8e2ab1f0f6edb16ff0bbd55fd42abbabfa0bbb78e31e4e9e8333beccHibiscus Flower DOCX is a Word Open XML Document sample based on Wikimedia Commons. It can be used to test downloads, parsers, previews, and file type detection.
08-hibiscus-flower.docxa77a5e581defd26e8dce364ee2de805ae26e5da346c76a5f651c8b51c2774111Arctic Sky DOCX is a Word Open XML Document sample based on Wikimedia Commons. It can be used to test downloads, parsers, previews, and file type detection.
09-arctic-sky.docx2cd4ca0ad25fb60fca45a22f258c6192c86ddb0c692f2e8456774aa7d877cbb7Sunset Rays DOCX is a Word Open XML Document sample based on Wikimedia Commons. It can be used to test downloads, parsers, previews, and file type detection.
10-sunset-rays.docxc84d64f4acb2619f46470635e9297e70176651cfbb11506c698bee85d03cbb03NASA Blue Marble DOCX is a Word Open XML Document sample based on NASA Image and Video Library. It can be used to test downloads, parsers, previews, and file type detection.
nasa-blue-marble-2012-east.docxb2cdfa34dc8f4c1c102ade1829c7cb322bbd2c6e4fa5358c9c44f5ed992abd27Word Open XML Document files begin with the byte signature 50 4B 03 04 ("PK.."). Detect the format by reading these leading bytes rather than trusting the file extension alone.
The MIME type for Word Open XML Document is application/vnd.openxmlformats-officedocument.wordprocessingml.document.
Word Open XML Document files use the .docx extension. The extension is a convention only and does not guarantee the file contents, so combine it with signature and structure checks.