20 posts tagged “pyodide”
2025
If you want to create completely free software for other people to use, the absolute best delivery mechanism right now is static HTML and JavaScript served from a free web host with an established reputation.
Thanks to WebAssembly the set of potential software that can be served in this way is vast and, I think, under appreciated. Pyodide means we can ship client-side Python applications now!
This assumes that you would like your gift to the world to keep working for as long as possible, while granting you the freedom to lose interest and move onto other projects without needing to keep covering expenses far into the future.
Even the cheapest hosting plan requires you to monitor and update billing details every few years. Domains have to be renewed. Anything that runs server-side will inevitably need to be upgraded someday - and the longer you wait between upgrades the harder those become.
My top choice for this kind of thing in 2025 is GitHub, using GitHub Pages. It's free for public repositories and I haven't seen GitHub break a working URL that they have hosted in the 17+ years since they first launched.
A few years ago I'd have recommended Heroku on the basis that their free plan had stayed reliable for more than a decade, but Salesforce took that accumulated goodwill and incinerated it in 2022.
It almost goes without saying that you should release it under an open source license. The license alone is not enough to ensure regular human beings can make use of what you have built though: give people a link to something that works!
URL-addressable Pyodide Python environments
This evening I spotted an obscure bug in Datasette, using Datasette Lite. I figure it’s a good opportunity to highlight how useful it is to have a URL-addressable Python environment, powered by Pyodide and WebAssembly.
[... 1,905 words]APSW SQLite query explainer. Today I found out about APSW's (Another Python SQLite Wrapper, in constant development since 2004) apsw.ext.query_info() function, which takes a SQL query and returns a very detailed set of information about that query - all without executing it.
It actually solves a bunch of problems I've wanted to address in Datasette - like taking an arbitrary query and figuring out how many parameters (?) it takes and which tables and columns are represented in the result.
I tried it out in my console (uv run --with apsw python) and it seemed to work really well. Then I remembered that the Pyodide project includes WebAssembly builds of a number of Python C extensions and was delighted to find apsw on that list.
... so I got Claude to build me a web interface for trying out the function, using Pyodide to run a user's query in Python in their browser via WebAssembly.
Claude didn't quite get it in one shot - I had to feed it the URL to a more recent Pyodide and it got stuck in a bug loop which I fixed by pasting the code into a fresh session.
2024
ChatGPT Canvas can make API requests now, but it’s complicated
Today’s 12 Days of OpenAI release concerned ChatGPT Canvas, a new ChatGPT feature that enables ChatGPT to pop open a side panel with a shared editor in it where you can collaborate with ChatGPT on editing a document or writing code.
[... 1,116 words]ChainForge. I'm still on the hunt for good options for running evaluations against prompts. ChainForge offers an interesting approach, calling itself "an open-source visual programming environment for prompt engineering".
The interface is one of those boxes-and-lines visual programming tools, which reminds me of Yahoo Pipes.
It's open source (from a team at Harvard) and written in Python, which means you can run a local copy instantly via uvx like this:
uvx chainforge serve
You can then configure it with API keys to various providers (OpenAI worked for me, Anthropic models returned JSON parsing errors due to a 500 page from the ChainForge proxy) and start trying it out.
The "Add Node" menu shows the full list of capabilities.
The JavaScript and Python evaluation blocks are particularly interesting: the JavaScript one runs outside of a sandbox using plain eval(), while the Python one still runs in your browser but uses Pyodide in a Web Worker.
Everything I built with Claude Artifacts this week
I’m a huge fan of Claude’s Artifacts feature, which lets you prompt Claude to create an interactive Single Page App (using HTML, CSS and JavaScript) and then view the result directly in the Claude interface, iterating on it further with the bot and then, if you like, copying out the resulting code.
[... 2,273 words]marimo.app. The Marimo reactive notebook (previously) - a Python notebook that's effectively a cross between Jupyter and Observable - now also has a version that runs entirely in your browser using WebAssembly and Pyodide. Here's the documentation.
Pyodide 0.26 Release (via) PyOdide provides Python packaged for browser WebAssembly alongside an ecosystem of additional tools and libraries to help Python and JavaScript work together.
The latest release bumps the Python version up to 3.12, and also adds support for pygame-ce, allowing games written using pygame to run directly in the browser.
The PyOdide community also just landed a 14-month-long PR adding support to cibuildwheel, which should make it easier to ship binary wheels targeting PyOdide.
Bringing Python to Workers using Pyodide and WebAssembly (via) Cloudflare Workers is Cloudflare’s serverless hosting tool for deploying server-side functions to edge locations in their CDN.
They just released Python support, accompanied by an extremely thorough technical explanation of how they got that to work. The details are fascinating.
Workers runs on V8 isolates, and the new Python support was implemented using Pyodide (CPython compiled to WebAssembly) running inside V8.
Getting this to work performantly and ergonomically took a huge amount of work.
There are too many details in here to effectively summarize, but my favorite detail is this one:
“We scan the Worker’s code for import statements, execute them, and then take a snapshot of the Worker’s WebAssembly linear memory. Effectively, we perform the expensive work of importing packages at deploy time, rather than at runtime.”
urllib3 2.2.0. Highlighted feature: “urllib3 now works in the browser”—the core urllib3 library now includes code that can integrate with Pyodide, using the browser’s fetch() or XMLHttpRequest APIs to make HTTP requests (to CORS-enabled endpoints).
2023
Weeknotes: sqlite-utils 3.31, download-esm, Python in a sandbox
A couple of speaking appearances last week—one planned, one unplanned. Plus sqlite-utils 3.31, download-esm and a new TIL.
2022
PyScript Updates: Bytecode Alliance, Pyodide, and MicroPython. Absolutely huge news about Python on the Web tucked into this announcement: Anaconda have managed to get a version of MicroPython compiled to WebAssembly running in the browser. Pyodide weighs in at around 6.5MB compressed, but the MicroPython build is just 303KB—the size of a large image. This makes Python in the web browser applicable to so many more potential areas.
Plugin support for Datasette Lite
I’ve added a new feature to Datasette Lite, my distribution of Datasette that runs entirely in the browser using Python and SQLite compiled to WebAssembly. You can now install additional Datasette plugins by passing them in the URL.
[... 865 words]Weeknotes: Datasette Lite, nogil Python, HYTRADBOI
My big project this week was Datasette Lite, a new way to run Datasette directly in a browser, powered by WebAssembly and Pyodide. I also continued my research into running SQL queries in parallel, described last week. Plus I spoke at HYTRADBOI.
[... 1,434 words]Datasette Lite: a server-side Python web application running in a browser
Datasette Lite is a new way to run Datasette: entirely in a browser, taking advantage of the incredible Pyodide project which provides Python compiled to WebAssembly plus a whole suite of useful extras.
[... 4,800 words]sqlite-utils 3.26.1 (via) I released sqlite-utils 3.36.1 with one tiny but exciting feature: I fixed its one dependency that wasn’t published as a pure Python wheel, which means it can now be used with Pyodide—Python compiled to WebAssembly running in your browser!
PyScript demos (via) PyScript was announced at PyCon this morning. It’s a new open source project that provides Web Components built on top of Pyodide, allowing you to use Python directly within your HTML pages in a way that is executed using a WebAssembly copy of Python running in your browser. These demos really help illustrate what it can do—it’s a fascinating new piece of the Python web ecosystem.
WebAssembly in my Browser Desktop Environment (via) Dustin Brett built the WebAssembly demo to end all WebAssembly demos: his daedalOS browser desktop environment simulates a Windows-style operating system, and bundles WebAssembly projects that include v86 for 486 emulation, js-dos for DOS emulation to run Doom, BoxedWine to run Wine applications like Notepad++, Ruffle to emulate Flash, ffmpeg.wasm to power audio and video conversion, WASM-ImageMagick for image conversion, Pyodide for a Python shell and more besides that!
2021
Weeknotes: datasette-jupyterlite, s3-credentials and a Python packaging talk
My big project this week was s3-credentials, described yesterday—but I also put together a fun expermiental Datasette plugin bundling JupyterLite and wrote up my PyGotham talk on Python packaging.
[... 476 words]2019
Pyodide: Bringing the scientific Python stack to the browser (via) More fun with WebAssembly: Pyodide attempts (and mostly succeeds) to bring the full Python data stack to the browser: CPython, NumPy, Pandas, Scipy, and Matplotlib. Also includes interesting bridge tools for e.g. driving a canvas element from Python. Really interesting project from the Firefox Data Platform team.