Klee is a native macOS AI assistant application that focuses on processing data locally to ensure security and privacy. It employs advanced AI technologies, such as RAG (Retrieval-Augmented Generation) and open-source large language models like Llama 3 and Mistral, providing users with efficient and intelligent note-taking, search, and knowledge management features. Key advantages of Klee include local operation for privacy protection, support for team collaboration, free usage, and an optimized macOS experience.