Ever found an interesting PCB design, but you are not able to open it with your favorite program? The world of EDA file formats is divided by vendors, with low flexibility to move from one program to another one. The design is for a proprietary program? Well you need to either buy the program, or hope to convert it to your favorite file-format using an error-prone conversation process. Not ideal, but better than nothing. This talk will show you the basics to write an importer yourself, with focus on reverse-engineering of the questionable file-format. Thus, going from seemingly arbitrary zeros and ones to the basic file structure and the actual data such as a track. While this is quite easy for text-based files such as the KiCad file format, binary files can be seen more like a puzzle to solve.