Simon Willison’s Weblog

Cloudflare Python Workers are now generally available (via) After a two year preview, Cloudflare's support for running Python code in their server-side Workers platform is now stable: "Python is now a first-class, fully supported language on the Cloudflare Developer Platform".

A neat thing about this is how it works. Cloudflare are running Python compiled to WebAssembly via Pyodide in their V8-based workerd runtime.

This comes with some limitations, documented here - most notably both multiprocessing and threading are non-functional in the WebAssembly VM.

One particularly interesting detail of this is the local development environment story - their pywrangler development tool (confusingly packaged as workers-py on PyPI) runs a full local simulation of their stack, including executing code with Pyodide in WebAssembly in V8 in a 123MB workerd binary, which for me ended up in node_modules/@cloudflare/workerd-darwin-arm64/bin/workerd.

Python Workers represent a significant investment in the wider Python ecosystem by Cloudflare. The release announcement is credited to Gyeongjae Choi, Dominik Picheta, and Hood Chatham - Gyeongjae and Hood are both Pyodide core maintainers.