marimo

What is marimo?

marimo is an open-source reactive notebook for Python that fundamentally rethinks how interactive computing should work. Unlike traditional Jupyter notebooks where cells can be run in any order and hidden state causes reproducibility nightmares, marimo treats notebooks as dataflow graphs. Run a cell or interact with a UI element, and marimo automatically runs all dependent cells -- keeping code and outputs perfectly synchronized at all times.

Every marimo notebook is stored as a pure Python file (not JSON like Jupyter), which means you can version control it with Git, execute it as a script from the command line, import it as a Python module, and deploy it as an interactive web application. This versatility is what separates marimo from incremental improvements to the Jupyter ecosystem -- it is a fundamentally different approach to interactive Python.

The project has accumulated 19.8K GitHub stars and is downloaded hundreds of thousands of times per month. It is used by enterprises including Cloudflare, Shopify, and BlackRock, as well as research institutions like Stanford, Johns Hopkins, and Princeton. Anthony Goldbloom, the founder and CEO of Kaggle, called marimo one of the few technologies that have been truly transformational for him. Samuel Colvin, the creator of Pydantic, said marimo solves all his frustrations with Jupyter elegantly.

Key Features

Reactive Execution

The core innovation. When you change a cell, marimo automatically identifies and reruns all cells that depend on it. There is no hidden state, no stale outputs, no out-of-order execution bugs. This reactive model eliminates the number one source of errors in traditional notebooks.

Pure Python Storage

Notebooks are stored as .py files, not JSON. This makes them git-friendly with clean diffs, executable as scripts, importable as modules, and deployable as web apps. One file format, five use cases.

Interactive UI Elements

Built-in sliders, dropdowns, tables, file uploads, and selectable plots that reactively update dependent cells. Build interactive data exploration tools and dashboards directly in your notebook.

Native SQL Support

Write SQL queries directly in marimo cells with support for DuckDB, SQLite, PostgreSQL, and MySQL. SQL results integrate seamlessly with Python code in the reactive dataflow graph.

AI-Native Editor

Built-in copilot-style autocomplete and AI assistance directly in the editor. Generate code, fix errors, and explore data with AI support that understands the notebook context.

App Deployment

Deploy any marimo notebook as a shareable web application with a single command. No separate deployment framework needed -- your notebook IS your app.

How to Use marimo

Pricing

marimo is completely free and open source under the Apache 2.0 license. There are no paid tiers, no feature gates, and no usage limits. The full platform -- including reactive execution, interactive widgets, SQL support, AI features, and app deployment -- is available to everyone at no cost.

Pros and Cons

marimo Alternatives

Alternative	Best For	Price
Jupyter Notebook	Traditional interactive Python	Free
Google Colab	Cloud notebooks with free GPUs	Free / $9.99/mo
Observable	JavaScript reactive notebooks	Free / $12/mo
Hex	Collaborative data workspaces	Free / $24/mo

Final Verdict

marimo earns a 4.7/5 and represents the most significant advancement in Python notebooks since Jupyter itself. The reactive execution model is not just a nice feature -- it fundamentally solves the reproducibility crisis that has plagued computational notebooks for years. The fact that it is completely free and open source makes the recommendation easy: if you work with Python for data science, research, or application development, you should try marimo.

The only reasons not to switch immediately are deep investments in Jupyter-specific extensions or workflows that depend on out-of-order execution (which marimo intentionally prevents). For everyone else, marimo's combination of reactive execution, pure Python storage, interactive widgets, SQL support, and one-command app deployment makes it the best notebook experience available.

Frequently Asked Questions