File with an .F3D extension contains a 3D project created in the 3D CAD project engineering software based on a cloud which enables data sharing and storing. Such files are stored on remote servers by default, however, they can be exported or stored on a local disc.

This extension is used by Autodesk Fusion 360 tool by default. Autodesk Fusion 360 was created in order to enable several engineers to work on a project simultaneously, which is why the data is stored in a cloud and can be accessed easily from any location.