AutoCAD 360 is a CAD project visualization software. It is compatible with DWG, DWF and DXF files and it lets you synchronize the application with your online AutoCAD 360 account.
This program includes zoom functions and an option to use two types of planes: model space and paper space. However, it does not allow any type of edition to the documents.
Autodesk AutoCAD 360 is free, but has limited functions. It is useful to have handy for professional projects.