DWG drawing viewer without AutoCAD
DWG is AutoCAD’s internal format, and it is closed: values are packed down to the bit, and every generation changes the packing. From 2004 onwards a scrambled header, paged sections and Autodesk’s own compression were added on top. That is why the usual advice for a DWG is "save it as DXF first" — advice that is useless exactly when AutoCAD is what you do not have. Here the drawing is read as it is: the generation is identified, the container unwrapped, the model-space objects decoded. The tool does not pretend to understand more than it does — whatever it could not decode is counted and left out, and the two generations it cannot open are named outright.
Drop a .dwg file in. The generation is decided by the first six bytes, so the extension does not matter — a .dwg.bak or a file with no extension works just as well.
The drawing appears on a white sheet and layers switch off one by one. Beside it: the AutoCAD generation, the object count, and whatever was left out.
DXF opens in any CAD program, including free ones. SVG opens in a browser and in vector editors.
