CrystalNets.jl is a Julia package which can be intuitively used from an interactive Julia shell or as an executable to determine the structure of single crystallographic files in the variety of file formats recognised by chemfiles . Since chemical bonds are not systematically present in such files, it uses a custom bond detection algorithm inspired from that of chemfiles, and can export both the input with the detected bonds as well as the extracted underlying net to allow visually checking the correspondence with the input. The bonding algorithm reuses available information on the structure to accurately account for the larger bonds surrounding metals in MOFs for instance, but the user can also override the cutoff distance for bonding if necessary.