JustHTML by @npub1ukcz...r8n2 is a new Python library (no dependencies) that parses HTML according to the HTML5 specification and passes the 9,200 test html5lib-tests suite It's 3,000 lines of code mostly written by coding agents over a couple of months

Simon Willison’s Weblog

JustHTML is a fascinating example of vibe engineering in action

I recently came across JustHTML, a new Python library for parsing HTML released by Emil Stenström. It’s a very interesting piece of software, bo...

OpenAI aren't talking about it yet, but it turns out they've adopted Anthropic's brilliant "skills" mechanism in a big way Skills are now live in both ChatGPT and their Codex CLI tool, I wrote up some detailed notes on how they work so far here:

Simon Willison’s Weblog

OpenAI are quietly adopting skills, now available in ChatGPT and Codex CLI

One of the things that most excited me about Anthropic’s new Skills mechanism back in October is how easy it looked for other platforms to implem...

Just pushed a new release of my LLM Python library and CLI tool for interacting with Large Language Models, adding support for GPT 5.1 and GPT 5.2 plus a few smaller bug fixes

Changelog - LLM

Initial notes on GPT-5.2 - I'm excited to see the knowledge cut-off bump up to August 2025, interesting that it's priced at 1.4x over GPT-5.1

Simon Willison’s Weblog

GPT-5.2

OpenAI reportedly declared a “code red” on the 1st of December in response to increasingly credible competition from the likes of Google’s Ge...