What it does
marimo is a Python programming environment for data exploration, teaching, and interactive applications. Its notebook editor tracks variable dependencies between cells, rerunning affected cells or marking them stale when a value changes. Unlike notebook formats that keep code and output together in a separate document format, marimo stores a notebook as Python source that can also be executed as a script or deployed as an app. Users can work locally or open the free molab cloud notebook in a browser.
Notebook cells follow the program's dependencies
In marimo, a useful first task is to load a small dataset in one cell, derive a summary in another, and plot that result in a third. When the input changes, the editor determines which dependent cells need to run; it does not rely only on the cells' position or on a user manually rerunning each one. This reactive model is intended to keep code, values, and output consistent. The example describes a documented workflow, not a notebook run for this record.
The project can be installed into a Python environment and opened with marimo edit notebook.py, or tried in the free molab browser environment. Notebook files are Python source, can be versioned with Git, and can be run as scripts or deployed as interactive apps. The docs also describe SQL queries over dataframes, databases, and other sources, with results returned as Python dataframes. The project repository publishes the software under the Apache 2.0 license.
marimo is a focused Python notebook environment rather than a general editor for unrelated programming languages. Local editing requires Python and an environment/package manager; molab is an alternative for browser-based work. The molab service and the local editor are related parts of the same project, not separate products in this listing.
Strengths
- Reactive execution follows variable dependencies and can mark expensive downstream cells stale instead of running them immediately.
- Notebooks are stored as Python source and can also run as scripts or be deployed as apps.
- The free molab service offers a browser-based way to create and share marimo notebooks.
- The official repository publishes the project under the Apache 2.0 license.
Watch out for
- The editor is centered on Python notebooks and data workflows, not general multi-language application editing.
- Local use requires a Python installation and a package-management workflow.
Best for
- Data scientists and researchers building reproducible Python analyses
- Educators sharing interactive code and data explanations
- Developers turning a notebook into a script or interactive data app
Sources
- marimo | a next-generation Python notebook (Oct 25, 2026)
- marimo - Documentation for the Reactive Python Notebook - marimo (Oct 25, 2026)
- Run in the cloud with molab - marimo (Oct 25, 2026)
- marimo/LICENSE at main · marimo-team/marimo · GitHub (Oct 25, 2026)