Marimo is an open-source reactive Python notebook that emphasizes reproducibility, is git-friendly, can be executed as scripts, and can be shared as applications. It automates the execution of affected cells in response to changes, removing the cumbersome task of managing notebook states. Marimo's UI elements, such as data frame GUIs and charts, make data processing swift, futuristic, and intuitive. Marimo notebooks are stored as .py files, compatible with git version control, executable as Python scripts, importable into other notebooks or Python files, and can be linted or formatted using your preferred tools—all within a modern AI-supported editor.