FAQ#

Choosing marimo#

How is marimo different from Jupyter?

marimo is a brand new Python notebook that is both interactive, with UI elements like sliders, dropdowns, etc., and reactive, like a spreadsheet. marimo solves many well-documented problems associated with traditional notebooks like Jupyter [1] [2]:

  • no hidden state: running a cell automatically runs all cells that depend on it, and deleting a cell automatically deletes its variables, eliminating hidden state and hidden bugs

  • interactive data exploration: UI elements and reactivity make your data tangible

  • sharing: use the marimo CLI to run notebooks as apps

  • Python, not JSON: stored as executable Python, with clean git diffs and potential for code reuse

  • fast, reliable autocomplete: code completion is fast and works out of the box

How is marimo.ui different from Jupyter widgets?

Unlike Jupyter widgets, marimo’s interactive elements are automatically synchronized with the Python kernel: no callbacks, no observers, no manually re-running cells.

Using marimo#

Is marimo a notebook or a library?

marimo is both a notebook and a library.

  • Create marimo notebooks with the editor that opens in your browser when you run marimo edit.

  • Use the marimo library (import marimo as mo) in marimo notebooks. Write markdown with mo.md(...), create stateful interactive elements with mo.ui (mo.ui.slider(...)), and more. See the docs for an API reference.

How does marimo know what cells to run?

marimo reads each cell once to determine what global names it defines and what global names it reads. When a cell is run, marimo runs all other cells that read any of the global names it defines. A global name can refer to a variable, class, function, or import.

In other words, marimo uses static analysis to make a dataflow graph out of your cells. Each cell is a node in the graph across which global variables “flow”. Whenever a cell is run, either because you changed its code or interacted with a UI element it reads, all its descendants run in turn.

How do I use sliders and other interactive elements?

Interactive UI elements like sliders are available in marimo.ui.

  • Assign the UI element to a global variable (slider = mo.ui.slider(0, 100))

  • Include it in the last expression of a cell to display it (slider or mo.md(f"Choose a value: {slider}"))

  • Read its current value in another cell via its value attribute (slider.value)

If you have many UI elements or don’t know the elements you’ll create until runtime, use marimo.ui.array and marimo.ui.dictionary to create UI elements that wrap other UI elements (sliders = mo.ui.array([slider(1, 100) for _ in range(n_sliders)])).

All this and more is explained in the UI tutorial. Run it with

marimo tutorial ui

at the command line.

How do I add a submit button to UI elements?

Use the form method to add a submit button to a UI element. For example,

form = marimo.ui.text_area().form()

When wrapped in a form, the text area’s value will only be sent to Python when you click the submit button. Access the last submitted value of the text area with form.value.

How do I write markdown?

Import marimo (as mo) in a notebook, and use the mo.md function.

How do I display plots?

Include plots in the last expression of a cell to display them, just like all other outputs. If you’re using matplotlib, you can display the Figure object (get the current figure with plt.gcf()). For examples, run the plots tutorial:

marimo tutorial plots

How do I display objects in rows and columns?

Use marimo.hstack and marimo.vstack. See the layout tutorial for details:

marimo tutorial layout

What packages can I use?

You can use any Python package. marimo cells run arbitrary Python code.

What’s the difference between a marimo notebook and a marimo app?

You can think of marimo programs as notebooks, apps, or both. Edit a marimo program as notebook with marimo edit, or run it as an app, rendering cell outputs without their code, with marimo run.

How do I deploy apps?

Use the marimo CLI’s run command to serve a notebook as an app:

marimo run notebook.py

Is marimo free?

Yes!