.ONE file signature
A One Note file begins with the bytes E4 52 5C 7B 8C D8 A7 4D AE B1 53 78 D0 29 96 D3 at the start of the file. The signature is the same whatever the file is named, which is why a renamed or extensionless ONE file is still recognisable.
Signature
| Offset | Hex | ASCII |
|---|---|---|
| 0 | E4 52 5C 7B 8C D8 A7 4D AE B1 53 78 D0 29 96 D3A 16-byte GUID identifying a OneNote section store. |
MIME type: application/onenote · usual extensions: .one
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.one
file file.oneWindows (PowerShell):
Format-Hex -Path file.one -Count 32If the bytes do not match
A file named .one whose first bytes are something else is not a ONE 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 ONE guide explains what a genuine file should contain.