LanguageGUI is an open-source design system and UI Kit that provides the flexibility to format text output from LLMs into rich graphical user interfaces. It includes dozens of unique UI elements that can be used for diverse use cases in conversational user interfaces. Key features include 100 customizable UI components and screens, 10 conversational UI widgets, 20 chat bubbles, 30 pre-built screens, 5 customizable chat sidebars, multiple tooltips, dark mode, and more. LanguageGUI is free to use for personal or commercial projects. It is developed by the Tonki Labs team and released under the MIT license.