LangFriend is a journaling app developed by LangChain to explore the concept of memory in large language models (LLMs), aiming to improve user experience by leveraging long-term memory for personalized interactions. The app draws inspiration from academic research, such as MemGPT and Generative Agents, which incorporate memory functions into LLMs, and from companies like Plastic Labs and Good AI, which are integrating long-term memory into AI systems. LangFriend’s journaling format is chosen to capture meaningful insights and feelings, allowing the app to remember and use this information to tailor responses. Users can customize the app's system prompts, enhancing its adaptability. The app serves as a research preview, encouraging community feedback to refine and expand its capabilities, ultimately showcasing the potential for memory integration to enhance generative AI applications.