Many people often wonder about how SHELXL has survived for more than half a century. It is a set of programs used for small molecule refinement in the chemistry laboratories of various universities. The origins of these programs go back to 1970s. The program was written on mainframe computers that occupied huge rooms and needed patient geniuses to operate and produced output on a line-printer. By the end of 1970s, the SHELXL set of programs became so big that it fitted almost 2000 punched cards (old way of storing data). These programs are obviously command line programs but they are still being used because they are very good. Many generations have improved these programs and they are not going away anytime soon.
Now to the new generations who do not want the command line interface, someone has developed a graphics user interface for SHELXL. This GUI is called ShelXle and works on any Linux or Windows PC. There are also versions that can be used on macOS. Obviously, this is only meant for the Chemistry students studying in various universities.
In order to start using ShelXle, you must first have some basic knowledge of the CLI programs SHELXL and what they do. In fact, we have to open the files that have been produced by SHELXL previously. In the interface of ShelXle, we can produce graphical representation of the three-dimensional molecular structure of various molecules that you are studying. It can display electron density maps as well as difference density maps.
ShelXle has been written fully in C++ and its source code is available for free. You can modify and compile it yourself. The developers have also published a small PDF document describing in brief all the features and functions that ShelXle offers. You can check this PDF document from https://journals.iucr.org/j/issues/2011/06/00/kk5092/kk5092.pdf.
You can download ShelXle from https://www.shelxle.org/.