File with a .BPN extension contains a backup copy of a project, that is created automatically by the BIM ArchiCAD software. BPN files are stored in a PLN format in the same directory as the original project file by default, and if it is damaged or deleted, the extension has to be changed from BPN into PLN.

ArchiCAD software is used to design, build and store information on buildings, in compliance with BIM. Enabling the project backup copy storing option in the applications security preferences enables its automatic saving in a defined time intervals.