STP Viewer - Free STP Viewer - free software that lets you view 3D STEP files (.stp, .step file format).
A360 VIEWER - Free online CAD Viewer
Glovius - Extensible & customizable 3D viewer, for consumption of product design data.
IGES2STEP - Freeware CAD file viewer for Windows XP/2000/NT
IDA-STEP Viewer - Component of IDA-STEP providing core viewing functionality for all kinds of STEP files (*.stp).
PartXplore - The most powerful, high-speed?CAD file viewer and analyzer