class marimo.Cell(_name: str, _cell: CellImpl, _app: InternalApp | None = None)

An executable notebook cell

A Cell object can be executed as a function via its run() method, which returns the cell’s last expression (output) and a mapping from its defined names to its values.

Cells can be named via the marimo editor in the browser, or by changing the cell’s function name in the notebook file. Named cells can then be executed for use in other notebooks, or to test in unit tests.

For example:

from my_notebook import my_cell

output, definitions = my_cell.run()

See the documentation of run for info and examples.

Public methods


Run this cell and return its visual output and definitions

Public Data Attributes:



The references that this cell takes as input


The definitions made by this cell

property refs: set[str]

The references that this cell takes as input

property defs: set[str]

The definitions made by this cell

run(**refs: Any) tuple[Any, Mapping[str, Any]] | Awaitable[tuple[Any, Mapping[str, Any]]]

Run this cell and return its visual output and definitions

Use this method to run named cells and retrieve their output and definitions.

This lets you use reuse cells defined in one notebook in another notebook or Python file. It also makes it possible to write and execute unit tests for notebook cells using a test framework like pytest.

Example. marimo cells can be given names either through the editor cell menu or by manually changing the function name in the notebook file. For example, consider a notebook notebook.py:

import marimo

app = marimo.App()

def __():
    import marimo as mo

    return (mo,)

def __():
    x = 0
    y = 1
    return (x, y)

def add(mo, x, y):
    z = x + y
    mo.md(f"The value of z is {z}")
    return (z,)

if __name__ == "__main__":

To reuse the add cell in another notebook, you’d simply write

from notebook import add

# `output` is the markdown rendered by `add`
# defs["z"] == `1`
output, defs = add.run()

When run is called without arguments, it automatically computes the values that the cell depends on (in this case, mo, x, and y). You can override these values by providing any subset of them as keyword arguments. For example,

# defs["z"] == 4
output, defs = add.run(x=2, y=2)

Defined UI Elements. If the cell’s output has UI elements that are in defs, interacting with the output in the frontend will trigger reactive execution of cells that reference the defs object. For example, if output has a slider defined by the cell, then scrubbing the slider will cause cells that reference defs to run.

Async cells. If this cell is a coroutine function (starting with async), or if any of its ancestors are coroutine functions, then you’ll need to await the result: output, defs = await cell.run(). You can check whether the result is an awaitable using:

from collections.abc import Awaitable

ret = cell.run()
if isinstance(ret, Awaitable):
    output, defs = await ret
    output, defs = ret


  • You may pass values for any of this cell’s references as keyword arguments. marimo will automatically compute values for any refs that are not provided by executing the parent cells that compute them.


  • a tuple (output, defs), or an awaitable of the same, where output is the cell’s last expression and defs is a Mapping from the cell’s defined names to their values.