This post lists down the best free 3D File Viewer software for Windows 11/10 to view and analyze 3D models & STL, etc, files.

Part of this is due to shortcomings in the STL file format. There’s a newer format available, 3MF, and Josef Prusa and Jakub Kočí would like you to start using it.

Microsoft has picked up Netfabb's 3D file cloud repair service, and renamed it Microsoft Model Repair. Features faster repair times thanks to new servers.

An imported STEP file is converted to a triangle mesh on import (making it much like a typical .stl or .3mf file) which means that slicing all happens as one would normally expect.