Intel / article

Cloudflare Python Workers are now generally available

Source: simonwillison.net
Date: Published Sep 21, 2026

From the Daily Brief

Cloudflare has taken Python Workers out of a two year preview and into general availability, giving Python first class status alongside JavaScript on its Developer Platform. The runtime compiles Pyodide to WebAssembly and executes it inside the V8 based workerd engine that already powers Cloudflare's JavaScript Workers, so Python code runs at the edge under the same deployment model.

The GA milestone comes with a clear limitation. Threading and multiprocessing are still unsupported, so workloads that depend on true parallelism within a single worker will not fit this runtime yet. That leaves Python Workers well suited to request handling, data transformation, and lightweight API logic, and less suited to CPU bound parallel jobs.

For developers who wanted to deploy production Python at the edge without waiting on beta support, this removes the last formal blocker. It also gives teams building agent tooling or lightweight inference glue in Python a serverless target that did not exist in stable form before, alongside the JavaScript and Rust runtimes Cloudflare already supports.

Read the 2026-09-22 Brief →

Context

Cloudflare has made Python a generally available language on Workers, its application runtime. The release announcement explains that Python runs through Pyodide, a version compiled for WebAssembly. The runtime also handles conversions between Python objects and Cloudflare services, removing glue code previously needed for operations such as sending a dictionary to a queue.

That execution environment determines which existing applications can move over. Native extensions need compatible WebAssembly builds, and the standard-library documentation says multiprocessing and threading can be imported but are nonfunctional. Developers gain a supported Python deployment option whose package and concurrency requirements need to match this runtime.

Key takeaways · AI-distilled

Cloudflare's Python Workers reached general availability after a two-year preview, running CPython compiled to WebAssembly via Pyodide inside Cloudflare's V8-based workerd runtime.
The WebAssembly has real limits: both multiprocessing and threading are non-functional for Python code running in Workers.
Local development runs a full simulation of the production stack, including a roughly 123MB workerd binary executing Pyodide-compiled Python in WebAssembly, via a tool called pywrangler (packaged as workers-py on PyPI).
The release is credited to Gyeongjae Choi, Dominik Picheta, and Hood Chatham; two of the three (Choi and Chatham) are core maintainers of the Pyodide project itself.

Terms in this piece · Glossary

sandbox — An isolated environment where AI-generated code or agent actions run without being able to touch anything real.

Read the source simonwillison.net