Marimo – open-source reactive Python notebook – running in WASM
Hi HN! Last month, we shared marimo [1][2], an open-source reactive notebook for Python. For those who missed it, marimo notebooks are reproducible, stored as Python files, executable as Python scripts, and deployable as web apps. It’s now possible to run marimo notebooks entirely in the browser via WebAssembly (WASM). - A marimo tutorial as a WASM notebook: https://marimo.app/l/c7h6pz - Training a neural network with Karpathy’s micrograd: https://marimo.app/l/xpd4te - Visualizing attractors, as a read-only app:…
In plain words
Marimo is an open-source reactive notebook for Python that can run entirely in a web browser via WebAssembly. Notebooks are stored as Python files, executable as scripts, and deployable as web apps. Users can write and experiment with Python code without installing it locally, and easily share notebooks through generated links. It's designed for data scientists, educators, and developers who want reproducible, shareable computational environments.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
Hi HN! Last month, we shared marimo [1][2], an open-source reactive notebook for Python. For those who missed it, marimo notebooks are reproducible, stored as Python files, executable as Python scripts, and deployable as web apps. It’s now possible to run marimo notebooks entirely in the browser via WebAssembly (WASM). - A marimo tutorial as a WASM notebook: https://marimo.app/l/c7h6pz - Training a neural network with Karpathy’s micrograd: https://marimo.app/l/xpd4te - Visualizing attractors, as a read-only app: https://marimo.app/l/e9wii1?mode=read - A blank notebook: https://marimo.new - Docs: https://docs.marimo.io/guides/wasm.html WASM notebooks let you experiment with code without having to install Python on your machine. These notebooks can be easily shared — marimo includes a button that generates a marimo.app URL (code encoded as a query parameter), and marimo.app has a built-in permalink generator. We also support embedding via iframes: you can use this to (say) author interactive documentation or standalone interactive blog posts. We now in fact use embedded WASM notebooks throughout our API docs. Our WASM notebook is powered by Pyodide [3], a WASM-based Python distribution. Pyodide can run any Python package that has a pure Python wheel, as well as many popular libraries for scientific computing and machine learning, including Pandas, NumPy, SciPy, and scikit-learn. Over time, we expect more and more libraries to be packaged for Pyodide. We’re very excited by the potential of WASM notebooks to make computing more accessible, and we’re in awe of all that the WASM and Pyodide contributors have accomplished. We have lots more planned (one example: we plan to make it easy to work with local files), and hope to share new developments with you in the future. In the meantime, please try https://marimo.app out. We’d appreciate feedback! P.S. Our support for WASM is very new; you may encounter sharp edges. Still, since WASM-compatibility was one of the most requested features from our previous HN, we felt it was worth sharing. [1] https://news.ycombinator.com/item?id=38971966 [2] https://github.com/marimo-team/marimo [3] https://github.com/pyodide/pyodide
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