A SKB file is a backup document created by the Windows version of SketchUp, a free 3D modeling program. It contains a backup of a .SKP SketchUp 3D model. SKB files are saved automatically using the program's auto-save feature in case the original SKP file becomes corrupted or is accidentally deleted.

SKB files are only created by the Windows version of SketchUp and appear as [filename].skp. The macOS version autosaves models with the ".skp" extension as [filename]~.skp. SKB files are typically saved in the "My Documents" folder with the original SKP file. However, the location can be changed by selecting Preferences → Files → Models.... SKB files contain the version of the model that was saved before the current version of the model in the SKP file. If you are having trouble opening the SKB file, you may need to change the extension from ".skb" to ".skp" in order to open it. SketchUp is primarily used to create 3D models related to architecture, interior design, film, video game design, and mechanical engineering. It is free to download.