BotPsy is an on-device personal assistant developed by Hugging Face, leveraging a sub-billion-parameter agentic language model. The assistant is designed to operate on-device, eliminating the need for cloud connectivity and enabling users to maintain their personal data and conversations on their devices. BotPsy's language model is based on a novel architecture that integrates a state-of-the-art transformer and a hierarchical attention mechanism. This setup allows the model to efficiently process and respond to user queries while ensuring data privacy and security. The assistant's capabilities include conversational dialogue management, task-oriented reasoning, and multimodal interaction. BotPsy's on-device deployment and agentic language model make it an attractive solution for applications where data protection and user privacy are paramount, such as in IoT devices, smart homes, and other edge computing scenarios.