To design a CAD viewer on the Web, a file translation system which converts a native CAD file of a commercial CAD to the simplified CAD file is required. However, commercial CAD viewers have used simplified geometric data similar to the VRML format. Thus, it has been difficult to apply such data to the accurate design and dimension examination procedures. In this paper, a STEP translation server supporting most CAD native formats is devised. To apply the STEP file to the precise CAD viewer, an accurate geometric data extraction method from the STEP file is studied. A STEP translator classifies and defines geometric shapes according to the boundary information. Viewing and measurement functions of the developed system verify the geometries, interferences, dimensional errors, human factors, and form errors of the CAD data. In addition, design modification messages are transferred through the markup functions of the system. Collaborators are able to share their design ideas and opinions rapidly and remotely through the XML (eXtensible Markup Language) open architecture. The effectiveness of the developed system is confirmed through case studies.