You can view 3DS files online using a dedicated free service. Some of the online tools that you can try are AutodeskViewer.com, 3DViewerOnline.com, 3DUsher.com, etc. If you want to use a free desktop application, you can check out this article. Here, we have mentioned some great free 3D model viewers that you can use to view 3DS and other 3D files on Windows PC.