Weex UI is a JavaScript framework that is built on top of Weex, a modern JavaScript framework for building real-time mobile apps. It is designed to be fast, scalable, and easy to use, making it a popular choice for building complex, multi-component applications. It includes a wide range of pre-built UI components and tools, as well as a comprehensive API for building custom functionality. With Weex UI, developers can create engaging and interactive user experiences on both iOS and Android platforms.