.DEX file signature
A Dalvik dex file file begins with the bytes 64 65 78 0A 30 33 35 00 (dex\n035\0 in ASCII) at the start of the file. The signature is the same whatever the file is named, which is why a renamed or extensionless DEX file is still recognisable.
Signature
| Offset | Hex | ASCII |
|---|---|---|
| 0 | 64 65 78 0A 30 33 35 00The three digits are the format version (035, 037, 038, 039). | dex\n035\0 |
MIME type: application/octet-stream · usual extensions: .dex
How to check a file's signature
Without installing anything: drop the file on our detector. It reads the bytes in your browser and shows the hex dump alongside the verdict; nothing is uploaded.
macOS and Linux (Terminal):
xxd -l 32 file.dex
file file.dexWindows (PowerShell):
Format-Hex -Path file.dex -Count 32If the bytes do not match
A file named .dex whose first bytes are something else is not a DEX file. The common explanations are a wrong or deliberately misleading extension, a download that saved an HTML error page instead of the file, or a container such as ZIP wrapping the real content. The detector reports what the bytes say; the DEX guide explains what a genuine file should contain.