HeyJaredSimon Willison’s Newsletter
AI, LLMs, web engineering, open source, data science, Datasette, SQLite, Python and more
- Indexed issues, last 90 days
- 13
- Latest publication
- Sep 28, 2026
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- Jul 5, 2026
Latest issues
2026 in LLMs (so far) (opens the original)
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In this newsletter:2026 in LLMs (so far)Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price warPlus 1 link, 3 quotations, 1 note, 5 releases, 4 tools, and 2 commentsThanks for reading Simon Willison’s Newsletter! Subscribe for free to receive new posts and support my work.<input class="button primary" type="submit" value="
Jev introduces a new shape of LLM - System One, aka Decision Models (opens the original)
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In this newsletter:Jev introduces a new shape of LLM - System One, aka Decision ModelsPlus 8 links, 3 quotations, 1 note, 5 releases, 1 tool, and 1 commentSponsor message: Pressure wash your codebase with LLMs to find vulnerabilities.Human bandwidth is no longer the issue when it comes to finding software security bugs – but keeping experienced human experts in the loop matters. LLMs are now exceptional at finding security vulnerabilities with simple prompting. Teleport dedicated 13 of their bes
Navier–Stokes, RubyGems attacked, GIS and Blender with GPT-6 Astra (opens the original)
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In this newsletter:Some thoughts on the Navier–Stokes Millennium Prize ProblemGenerating running routes with GPT-6 Astra and ChatGPT WorkOpenAI agents attacked RubyGems back in MayPlus 7 links, 7 quotations, 1 note, 7 releases, 3 tools, and 2 commentsSponsor message: Agents are the new front door to your app. auth.md by WorkOS is an open protocol that lets them register users on the fly, with the flows and scopes you choose and short-lived tokens over standard OAuth. Cloudflare, Resend, and Fire
GPT-6 Astra, Claude Fable 5.1, and yet more rogue agent attacks (opens the original)
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In this newsletter:The Pelican comparison grid for Astra is pretty interestingOpenAI’s rogue agents were caught communicating via public wikisClaude Fable 5.1 made me a really nice animated pelicanClaude’s new system prompt really doesn’t want to reproduce song lyricsPlus 6 links and 4 quotations and 2 notes and 2 releases and 1 TIL and 1 tool and 1 commentSponsor message: AI agents are your fastest-growing security risk. Portnox delivers Zero Trust for AI, partnering with CrowdStrike, SentinelO
Understanding ChatGPT Work (opens the original)
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In this newsletter:Understanding ChatGPT WorkPlus 6 links and 1 quotation and 1 releaseSponsor message: Static code review has a ceiling. It can reason about what the code says. It can’t tell you what it does. TREX (which stands for “Test, Run, Execute”) is Greptile’s response to that ceiling: an execution layer built directly into code review. Try it for free.<a href="https://simonwillison.net/2026/Aug/30/understanding-chatgpt-work/
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