A360 VIEWER - Free online CAD Viewer
STP Viewer - Free STP Viewer - free software that lets you view 3D STEP files (.stp, .step file format).
Glovius - Extensible & customizable 3D viewer, for consumption of product design data.
Autodesk DWG TrueView - Get a free DWG viewer to view, open, edit, and convert .dwg files, the native file format for AutoCAD files. DWG Trueview includes DWG TrueConvert.
IDA-STEP Viewer - Component of IDA-STEP providing core viewing functionality for all kinds of STEP files (*.stp).
DWGSee - A lite and fast dwg viewer, let you view, print, markup, measure dwg files. Supports AutoCAD 2020 drawing format!