Release: pwasm 0.2a0
Simon Willison’s Weblog
Subscribe
1st October 2026
Release
pwasm 0.2a0 — A WebAssembly engine in pure Python
pwasm is one of my folly projects - an entirely vibe-coded pure Python WebAssembly engine that I built in January during my first bout of AI mania.
I hadn't touched it since January, so I decided to let Claude Opus 5.5 loose on it and see if it could make any significant improvements:
Evaluate current state of pwasm - then consider what it would take to get the MicroPython and micro JavaScript experiments from the research repo working under it - and what it would take to speed it up
42 commits later (with minimal follow-up prompting) it now handles almost all of the WASM specification and the wheel from PyPI bundles working WASM builds of MicroPython, QuickJS and Micro QuickJS.
I wouldn't trust this thing at all - hence the alpha version tag - but it's interesting seeing how today's models can improve on the work of models from 10 months ago.
Recent articles
We're going to need default hard budget caps on pretty much everything - 3rd October 2026
OpenAI DevDay 2026 live blog - 29th September 2026
2026 in LLMs (so far) - 27th September 2026
This is a beat by Simon Willison, posted on 1st October 2026.
Monthly briefing
Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments.
Pay me to send you less!
Sponsor & subscribe
Disclosures
Colophon
©
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026