Pleasant3D visualizes STL and GCode files. It's also possible to do basic editing on STL files (moving/resizing the object etc.).
Last but not least, you can use Pleasant3D to convert ASCII STL files to binary STL.
What's new in version 2.6.4
ReleaseSeptember 2, 2016
Date AddedSeptember 2, 2016
Operating SystemsMac OS X 10.11, Macintosh, Mac OS X 10.9, Mac OS X 10.10, Mac OS X 10.8, Mac OS X 10.7