SHELX is a set of programs for the determination of small (SM) and macromolecular (MM) crystal structures by single crystal X-ray and neutron diffraction. These stand-alone executables require NO libraries, extra files or environment variables. They are compatible with all modern versions of Linux, Windows and MacOSX, and are free for academic use. For-profit users are expected to pay a licence fee that covers development and support for all users.