We all know The Muppet Christmas Carol is the perfect Christmas movie (and the definitive movie version of that novel) already... but did you know the Muppets' costumes are all era-appropriate - and their styles for the 1780s, 1790s, 1840s are all different! www.tiktok.com/@littlebloss...

GPT-5.2 Codex is the first model to decide that pelicans should ride their bicycles in the desert simonwillison.net/2025/Dec/19/...

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 simonwillison.net/2025/Dec/18/...

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 simonwillison.net/2025/Dec/17/...

Blogged some notes on the new ChatGPT Images model that launched today simonwillison.net/2025/Dec/16/...

Given their reputation for inaccuracy it feels a little absurd to ask an LLM to fact check something, but I've been getting similar high quality results from the best search-tool-using models recently for the prompt "fact check this"

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 simonwillison.net/2025/Dec/15/...

JustHTML by @emilstenstrom.bsky.social 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 simonwillison.net/2025/Dec/14/...

Congratulations to the new #Python #SteeringCouncil! 🗳️ @pumpichank.bsky.social 🗳️ @corona10.bsky.social 🗳️ @pablogsal.com 🗳️ @savannah.dev 🗳️ @yhg1s.bsky.social discuss.python.org/t/steering-c... Welcome Savannah & thank you to @gpshead.bsky.social for your service! hugovk.github.io/python-steer...

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: simonwillison.net/2025/Dec/12/...

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 llm.datasette.io/en/stable/ch...

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 simonwillison.net/2025/Dec/11/...

I put together a detailed collection of useful patterns I've collected after vibe-coding 150 different single-file HTML tools over the past couple of years simonwillison.net/2025/Dec/10/...

I've never been particularly invested in light mode v.s. dark mode but I got enough complaints from people that my blog was "blinding" that I had Claude Code knock out a dark mode theme for it, and it seems to work pretty well simonwillison.net/2025/Dec/10/...

Outstanding news for Kākāpō breeding season: it's a bumper year for the Rimu trees!! www.tiktok.com/@nzherald/vi...

Put together some notes on Mistral Vibe, Mistral's new CLI coding agent (think Claude Code / OpenAI Codex) which is Apache 2 licensed, written in Python+Pydantic+Textual and has a neat set of system and tool definition prompts that are fun to read simonwillison.net/2025/Dec/9/m...

I finally made it to The Museum of Jurassic Technology today! It's been top of my list of want-to-go museums for years www.niche-museums.com/116

I thoroughly recommend reading all of Cory Doctorow's recent speech on AI skepticism, it's crammed with new arguments and interesting new ways of thinking about these problems pluralistic.net/2025/12/05/p...

Let's build hyper-personalized AI-powered software that avoids the attention hijacking anti-patterns that defined so much of the last decade of software design - here's our manifesto with principles on how we can do that - more thoughts on my blog: simonwillison.net/2025/Dec/5/r...

Some notes on the two features in the newly released Django 6 that most caught my eye: background workers and template partials simonwillison.net/2025/Dec/4/d...

Four new models from Mistral today - all Apache 2 licensed, all vision-capable, and one of them is a 3GB model that can run in a web browser and answer questions about things it can see through the webcam! simonwillison.net/2025/Dec/2/i...

Notes and pelicans for today's pair of DeepSeek v3.2 model releases simonwillison.net/2025/Dec/1/d...

I see a lot of this distrust in online conversations too - I think it represents a concerning media literacy problem There's a big difference between reporting from professional journalists at reputable news organizations and the lies and distortions that make up much of today's media landscape

To Opus 4.5: "Artifact, no react, with an interactive explainer of how octaves work - should include buttons to press to make sounds and frequency visualizations, make the design minimal, but have a lot of subtle puns" tools.simonwillison.net/octave-expla...

A tiny TIL: if you get "Error 153: Video player configuration error" on YouTube videos embedded on your site a likely culprit is sending the "Referrer-Policy: same-origin" HTTP header Switching to "strict-origin-when-cross-origin" fixed it for me: simonwillison.net/2025/Dec/1/y...

I enjoyed this TikTok about procedural generation and AI in video games mainly for the line "there's so much to explore and nothing to find" www.tiktok.com/@nobody.impo...

It's ChatGPT's third birthday today, so I pulled other some quotes from the early months of ChatGPT on my blog OpenAI really did not expect it to be as popular as it was! simonwillison.net/2025/Nov/30/...

Point 2 here is very true

I think one of the underrated things about LLMs for coding is that they make writing code on a mobile phone massively more feasible I can build small but useful pieces of software entirely on my phone now - without even needing to pay full attention, so it's compatible with being out in the world

Out of curiosity I decided to try and run the numbers on how much Netflix you can watch for the energy cost of a ChatGPT prompt As far as I can tell it's between 5.1 and 10.2 seconds, depending on which end of the 2019 IEA Netflix energy usage estimate you use simonwillison.net/2025/Nov/29/...

I've been having a bunch of fan hacking on my Bluesky thread viewing HTML+JS app using Claude Code - here's a video demo of the most recent version, you can try it out here tools.simonwillison.net/bluesky-thre...

It's been nearly eleven months since this post and Google AI overviews STILL tells me Encanto 2 is "set for release in the US on August 25, 2024" I wonder if this bug will make it to its one year birthday next month

At the risk of starting the flame war to end all flame wars... Modern LLMs (GPT-5.1, Claude 4.5, Gemini 3) produce excellent code and can be a significant productivity boost to software engineers who take the time to learn how to effectively apply them - especially if used with coding agent tools

DeepSeek-Math-V2 means we now have an open weights (Apache 2) model that can achieve gold medal performance on this year's International Mathematical Olympiad - previously proprietary models from OpenAI and Google DeepMind had achieved that 689GB from Hugging Face! simonwillison.net/2025/Nov/27/...

I'm in an episode of the new Data Renegades podcast with CL Kao and Dori Wilson talking about data journalism and Datasette and related topics - it's a fun conversation, here are some extracted highlights simonwillison.net/2025/Nov/26/...

PromptArmor have a nasty description of a prompt injection attack against Google's new Antigravity AI IDE which can result in credentials (like AWS keys) being stolen by an attacker: www.promptarmor.com/resources/go... My notes here: simonwillison.net/2025/Nov/25/...

Initial impressions (and pelicans) of Claude Opus 4.5, Anthropic's new "best model in the world for coding" released this morning. simonwillison.net/2025/Nov/24/...

I love these skits by Shannon Fiedler - the density of jokes and the pace of the editing are both pretty astonishing www.tiktok.com/@shannonfied...

Annotated release notes for the new sqlite-utils alpha, which includes several minor backwards incompatible changes that will be released in the stable 4.0 version once the new alpha has baked for a while simonwillison.net/2025/Nov/24/...

Olmo 3 is notable as a "fully open" LLM - all of the training data is published, plus complete details on how the training process was run. I tried out the 32B thinking model and the 7B instruct models, + thoughts on why transparent training data is so important simonwillison.net/2025/Nov/22/...

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Pluribus on Apple TV is such a great show - infuriatingly difficult to recommend though since it's so easy to spoil the experience if you share too many details Just watch it, it's great!

Nano Banana Pro, released this morning, is clearly the best image generation model. Superb instruction following, plus it can generate full infographics (with correct spelling and properly rendered text!) from a short prompt based on running extra searches simonwillison.net/2025/Nov/20/...

Notes on GPT-5.1-Codex-Max - remember when GPT-5 was meant to signal and end to confusing model names? simonwillison.net/2025/Nov/19/...

Made a video demonstrating the slightly absurd collection of digital duct tape I use to automate the sending of my Substack newsletter, despite Substack not offering an API www.youtube.com/watch?v=BoPZ...

New llm-gemini plugin release for my LLM CLI tool, in addition to Gemini 3 support it also adds the ability to pass in a YouTube URL as an attachment in order to analyze that video using Gemini simonwillison.net/2025/Nov/18/...

Just found out that MacWhisper, my favorite macOS app for transcribing audio to text (using Whisper or now also NVIDIA Parakeet) now has an Automatic Speaker Recognition feature too simonwillison.net/2025/Nov/18/...

My notes on Google's new Antigravity IDE - at first glance it looks like yet another VS Code fork but there are some interesting new ideas in there simonwillison.net/2025/Nov/18/...

My notes on Gemini 3, including analyzing a 3.5 hour council meeting audio recording and performance on a new, improved version of my pelican on a bicycle benchmark simonwillison.net/2025/Nov/18/...

New release of my llm-anthropic plugin adding support for structured outputs (via the new official API - previously I faked it with tool calls) and Anthropic's web search feature github.com/simonw/llm-a...