Function

• CAD viewing software allows a user without a CAD program to look at drawing files. As the drawing is in its original format, there is no loss of information. CAD viewers cannot allow any changes to be made to the file. Most CAD viewers are able to print the drawing.
  
  

Program-Specific Viewers

• Most CAD program makers provide free CAD viewers. These are specific to their software format and, therefore, will only open files produced by that CAD program. These viewers can usually be obtained from the vendor's website.
  
  

General Viewers

• Some CAD programs enable viewing of several different file types. This can be useful if working in a mixed program environment. It also means you only need one program to view all your CAD drawings.