OneNote

OneNote is a Microsoft application for note taking and similar tasks, with a focus on multi-user collaboration.

Most editions have a native .one file format. It's not clear, but some cloud-only editions might not have any way to save to a local file at all (though you could maybe still Print to a file).

Identification
Some or all .one files begin with bytes. This represents the GUID {7B5C52E4-D88C-4DA7-AEB1-5378D02996D3}, which is a code for the file type.

.onetoc2 files begin with.

.onepkg is based on Cabinet format.

Specifications

 * &#x5b;MS-ONESTORE&#x5d;: OneNote Revision Store File Format
 * &#x5b;MS-ONE&#x5d;: OneNote File Format

Links

 * Microsoft OneNote
 * OneNote website / web app