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.
VariCAD Viewer - 3d cad,mechanical cad,mechanical engineering,linux cad
PartXplore - The most powerful, high-speed?CAD file viewer and analyzer
IDA-STEP Viewer - Component of IDA-STEP providing core viewing functionality for all kinds of STEP files (*.stp).