DemoGPT is an open-source Python project designed to demonstrate the core concepts of AI agents using OpenAI's GPT models. It implements a conversational interface with persistent memory saved in JSON files, enabling context-aware interactions across sessions. The framework supports dynamic tool execution, such as web search, calculations, and custom extensions, through a plugin-style architecture. By simply configuring your OpenAI API key and installing dependencies, users can run DemoGPT locally to prototype chatbots, explore multi-turn dialogue flows, and test agent-driven workflows. This comprehensive demo offers developers and researchers a practical foundation for building, customizing, and experimenting with GPT-powered agents in real-world scenarios.