Simon Willison

Simon Willison's avatar
Simon Willison
simon_at_fedi.simonwillison.net@momostr.pink
npub1gv26...tlwl
Open source developer building tools to help journalists, archivists, librarians and others analyze, explore and publish their data. https://datasette.io and many other #projects. Blog: https://simonwillison.net GitHub: https://simonw.github.io Twitter: https://twitter.com/simonw TIL: https://til.simonwillison.net
I see a lot of complaints about untested AI slop in pull requests. Submitting those is a dereliction of duty as a software engineer: Your job is to deliver code you have proven to work
Simon Willison’s Weblog
Your job is to deliver code you have proven to work
In all of the debates about the value of AI-assistance in software development there’s one depressing anecdote that I keep on seeing: the junior ...
Here's my article on Gemini 3 Flash, with four pelicans (one for each of its thinking effort levels) plus an image gallery Web Component that I had Gemini 3 Flash build specially for this post
Simon Willison’s Weblog
Gemini 3 Flash
It continues to be a busy December, if not quite as busy as last year. Today’s big news is Gemini 3 Flash, the latest in Google’s “Flash” l...
I ported a Python library implementing a full HTML5 parser to JavaScript using GPT-5.2 and Codex CLI in 4.5 hours, and decorated for Christmas and watched Knives Out while I was doing it
Simon Willison’s Weblog
I ported JustHTML from Python to JavaScript with Codex CLI and GPT-5.2 in 4.5 hours
I wrote about JustHTML yesterday—Emil Stenström’s project to build a new standards compliant HTML5 parser in pure Python code using coding age...
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...