.MKV file signature
A Matroska file begins with the bytes 1A 45 DF A3 at the start of the file. The signature is the same whatever the file is named, which is why a renamed or extensionless MKV file is still recognisable.
Signature
| Offset | Hex | ASCII |
|---|---|---|
| 0 | 1A 45 DF A3EBML header. The DocType string that follows reads matroska; WebM reads webm. |
MIME type: video/x-matroska · usual extensions: .mkv
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.mkv
file file.mkvWindows (PowerShell):
Format-Hex -Path file.mkv -Count 32If the bytes do not match
A file named .mkv whose first bytes are something else is not a MKV 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 MKV guide explains what a genuine file should contain.