Files with the .OBJ extension contain data of three-dimensional object such as 3D coordinates, maps of textures, and walls of polyhedra, saved in a universal format. OBJ files are supported by various applications for creating and editing 3D graphics.

The OBJ format is considered universal for 3D graphics editing programs. OBJ files also allow the use of surface shading thanks to references to one or more MTL files with materials.