Announcement

I’m the creator of Pytml, an open-source project that lets you write Python directly inside HTML and execute it in the browser using Pyodide. The idea is simple: add one script tag, write Python in a <py> block, and let Pyodide provide the Python runtime. <script src="https://pytml.vercel.app/pytml.js"></script> <py> print("Hello from Python!") </py> There is no Python server involved. The Python code runs in the browser. I originally built Pytml to make the first step into interactive web programming easier for people who already know, or are learning, Python. Along the way, the project became an experiment in how a relatively small JavaScript layer can connect Python to the browser DOM. ...

We are pleased to announce the Pyodide 314.0 release. This release focuses on standardization and packaging, marking a significant milestone in the Python-in-the-browser ecosystem. PEP 783 is Accepted: What Does It Mean? The acceptance of PEP 783: Emscripten packaging marks perhaps the most exciting change in the history of the Python-in-the-browser ecosystem. Pyodide maintainers—especially @hoodmane—have poured an immense amount of effort into this over a very long time. Achieving this long-standing goal will expand our ecosystem exponentially. ...

We are pleased to announce the Pyodide v0.29.0 release. This is a small feature release. toJs() and to_js() now convert dictionaries to Object instead of Map by default After much feedback from users, we changed toJs() and to_js() to convert dictionaries to Object by default. To opt into the old behavior, you can pass toJsLiteralMap: true to loadPyodide(). This will be removed in a future release. This was the main change motivating the feature release. ...

We are pleased to announce the Pyodide v0.28.0 release. This release focused on standardizing the Pyodide platform. Defining the Pyodide ABI In October 2024, the CPython steering council approved restoring Emscripten as a tier 3 target for CPython, starting from Python 3.14. We wrote PEP 776 – Emscripten Runtime support and PEP 783 – Emscripten Packaging in order to standardize the Emscripten target for CPython. PEP 783 aims to standardize the binary interfaces that Pyodide packages should follow, helping ensure compatibility with current and future versions of Pyodide. Our plan is to have one ABI per Python version. This means that packages built for a particular version of Pyodide will be compatible with all Pyodide versions that have the same version of Python. ...

Pyodide v0.27.0 is out. This release was focused on improving the long-term stability of Pyodide. Welcome Agriya Khetarpal to the Pyodide team Agriya Khetarpal has joined as a new maintainer. Agriya has been active in the Scientific Python area and is a contributor to NumPy, SciPy, and scikit-learn. He has already significantly strengthened Pyodide’s support for various Scientific Python packages. Build System Improvements Decoupling pyodide-build from Pyodide runtime pyodide-build is a tool that builds Python packages to run in Pyodide. Previously, the version of pyodide-build was strongly coupled to the version of Pyodide, meaning that if you wanted to build a package against a specific version of Pyodide, you had to use the corresponding version of pyodide-build. The problem with this approach was that even if we improved the build system, downstream users would have to wait for the next Pyodide release to use it. ...

Pyodide v0.26.0 is out, including Python version 3.12, many minor improvements to the foreign function interface and to the build system, and major improvements to stack switching. It also includes a tremendous amount of foward-looking work that is not yet visible to users. Pyodide at PyCon We were at PyCon again this year at another WebAssembly summit. The authors of this post met each other in person for the first time. Gyeongjae’s travel was generously paid for by our sponsors, so thank you if you have ever donated to Pyodide. Pyodide creator Mike Droettboom was there too. Both the WebAssembly summit and the rest of PyCon went fantastically well. It was wonderful hearing from the community about all of the things that are working well for them, and also very helpful to learn where we have room to improve. ...

We’re Akshay Agrawal and Myles Scolnick, and we’re the developers of marimo, an open-source reactive notebook for Python. In this post, we’ll describe how we ported marimo to work via Pyodide, and why we’re incredibly excited about the potential of Pyodide to make computing more accessible. What is marimo? marimo is an open-source reactive notebook for Python built from the ground up to solve well-known problems with traditional notebooks, including reproducibility, interactivity, maintainability, and shareability. ...

Happy New Year! Pyodide 0.25 is a major release with some exciting and experimental features. This major release includes requests library support, experimental support for JS Promise integration, and build system improvements. requests Support in Pyodide For a long time, the Pyodide community has been requesting support for the requests, Python’s popular HTTP client library. However, due to the limitations of Pyodide running in a browser environment, integrating networking libraries presented challenges. So, traditionally, if you needed to do something networking-related in Pyodide, you would need to use the pyfetch API, which is a wrapper around the browser’s fetch API. ...

Pyodide 0.24 is a major release focused on fine tuning public APIs and performance. It includes a major rework of the streams APIs to be faster and more flexible. We increased the consistency of the foreign function interface. We also added micropip support for the Python simple repository API. Performance Improvements Up to this point, we had not devoted much energy to performance improvements so there were many low-hanging fruit. ...

Pyodide 0.23 is a major release focused on updating CPython version to 3.11. It also brings several new features, enhancements, and bug fixes. This release includes updates to the Python standard library, deployment and build system enhancements, and new CLI commands. We also added several new packages to Pyodide, including fastparquet, pynacl and binary wheels for mypy. Note that there are several API deprecations; please refer to the changelog for details. ...