ONEPKG is a file extension usd by Microsoft Office OneNote application. ONEPKG file can be treated as a type of archive of documents (notes in form of ONE files) created using above-mentioned software. ONEPKG file is also used for exchanging informations between cooperating users.

ONEPKG archives are created by either importing or exporting sets of notes that are to be archived. ONEPKG file format is supported by 7-zip tool, and users who want to open such archive on Windows system can change its extension into ZIP. ONEPKG can also be used as document backup copies.