21st.dev is a platform offering React Tailwind components for design engineers, inspired by shadcn/ui. Built by the RorkAI team and Claude 3.5 Sonnet, it aims to help design engineers deliver sophisticated user interfaces more quickly. Users can install components with a single command, greatly improving development efficiency. The main advantages of this platform include its component-based and modular structure, making design and development work more flexible and efficient. Product background information indicates that it was created to meet the needs of design engineers for fast, high-quality UI components. Currently, the platform offers a free trial, but specific pricing information should be checked on its official website or by contacting customer service.