Do you need a free viewer for DWG files ?
If you want to view the DWG/DXF files on a Windows PC you can use the free Autodesk DWG TrueView. Autodesk DWG TrueView 2014 is the same exact software code as AutoCAD 2014 but limited to viewing, converting, publish/plot, and measuring. The plot feature uses the same plot configuration as AutoCAD. It is Autodesk DWG technology known as TrustedDWG. And it is free!
Highlights beyond View & Printing of a DWG:
- Convert DWG versions, bind Xrefs, purge, set default printer to “none”, audit and fix, replace page setups, and place all files in a Zip file or specified directory.
- Change visual styles
- Publish files as DWF and PDF files
- Measure objects
- Turn on/off layers
- Available in 32/64bit in English French Japanese languages
For Mac, mobile, mobile and cloud there is the free AutoCAD 360 https://www.autocad360.com/
"Autodesk® AutoCAD® 360 (formerly AutoCAD WS) is a free* web and mobile app that lets you view, edit, and share DWG™ files using a web browser or mobile device. Collaborate on designs with anyone, virtually anywhere. Store Autodesk® AutoCAD® technical and project files in an easy-to-access online workspace. Easily open and view .dwg, .dwf, and DXF™ files directly from email. AutoCAD 360 extends the power of AutoCAD beyond the desktop, making design review and approval easier than ever."