Marimo Notebooks

Marimo notebooks are reactive Python notebooks stored as pure .py files. Cells auto-execute when dependencies change, modeled as a directed acyclic graph (DAG).

Core Concepts

Reactivity Model

• marimo uses static analysis to build a dependency graph from variable references and definitions
• When a cell runs, all cells referencing its defined variables automatically re-run
• Execution order follows the dependency graph, not visual cell order
• Each global variable must be defined by exactly one cell
• marimo does not track object mutations (like list.append())—mutate in the same cell that creates the object, or create new variables

Avoiding Variable Name Conflicts

Each global variable must be defined by exactly one cell. Two strategies:

1. Wrap code in functions (preferred for reusable patterns):

@app.cell