Depending on your file's origin, download one of these industry-standard viewers: View BRD Files Easily with Altium Designer
If you need to open a PCB layout file with a extension, finding the right viewer depends entirely on which design suite created it. Because several major CAD programs use the same file extension for incompatible formats, you must match the viewer to the specific software used by the designer. 1. Top Recommended BRD File Viewers