NiceGUI is an open source Python library that enables developers to create web-based graphical user interfaces (GUIs) using only Python code. It provides a gentle learning curve while still offering the option for advanced customizations. NiceGUI follows a backend-first philosophy: it handles all the web development details, allowing developers to focus on writing Python code. This makes it ideal for a wide range of projects, including short scripts, dashboards, robotics projects, IoT solutions, smart home automation, and machine learning. The framework is built on FastAPI for backend operations, Vue.js for frontend interaction, and Tailwind CSS for styling. Developers can create buttons, dialogs, Markdown, 3D scenes, plots, and more, all within a Python environment. NiceGUI supports real-time interactivity through WebSocket connections, enabling instant updates in the browser without page reloads. It offers a variety of components and layout options, such as rows, columns, etc.