"An open source, portable, and extensible system for the processing and editing of unstructured 3D triangular meshes." Check your model for structural integrity. Useful for converting model files to .stl format.
Check and optimize your model before printing! Allows you to import and save .STL, .magics or .mgx files; compress .STL files; view parts as well as rotate, pan or zoom; and detect bad edges and flipped triangles. Download for free but requires registration.