We strongly recommend the use of a stand alone Gerber viewer. What you see is not always what you get. Don't assume that what you see in your design software is what the manufacturer will see. There are sometimes wide variations between what the design software shows and the output in the Gerber files. It's wise to use a third-party review to check your design. You will find that files output in 274-x format will import into most of these packages with no additional configuration needed.
Click Here to link to a 3rd-party Gerber Viewer vendor.
As you get closer to placing your PCB order, we highly recommend that you check out our FreeDFM tool. This tool can potentially save you money because we can help you determine if your Gerber Files are ready for manufacturing. Get your free graphical PCB board file check report in minutes.
See what our customers have to say about our free design for manufacturability tool: "DFM worked great! The files were interpreted correctly on the first try, it even caught my silkscreen error. The .pdf files showing the interpreted results of my Gerber files were excellent, very clear, detailed, as good as any check plots I've ever seen." -S. M., Mann Electronic Solutions