GuiXT is a client-server system that provides customizations to SAP user interfaces. It allows users to rearrange and modify SAP screen fields and layouts using a simple scripting language without affecting underlying ABAP code. GuiXT solutions improve productivity and accuracy. The free GuiXT editor allows modifying SAP screens by editing scripts. Optional add-ons like Designer, InputAssistant, and Viewer provide additional capabilities like automatically generating scripts, enhancing data entry workflows, and integrating SAP screens into ActiveX and HTML controls.