OpenAI DevDay 2026 AI

  • From the floor

    Curated from Simon Willison 29 September 2026

    OpenAI DevDay 2026 live blog

    Image from Simon Willison

    Simon Willison, who created Datasette and writes about language models, live-blogged the keynote from a creator seat OpenAI provided, then the afternoon sessions: ChatGPT Sites, which already hosts 8 million sites, each with its own SQLite database; Codex Security, whose internal sprint at OpenAI fixed 53 critical findings on its first day, found 36 per cent of its discoveries were duplicates and shipped patches with a 1 per cent rollback rate; and a GPT-Live session with the model as a third presenter. Read it for what happened in the room, minute by minute.

    From Simon Willison

    10:13 Live demo! "Dottie is having a slow morning" - we got a "still checking" and an embarrassing silent moment.

    [...]

    10:24 Also today: previewing a new Decisions API. Lets the model respond "in a fraction of a second". It works by giving the Luna model "a predefined set of options to choose from". Sounds like their response to Jev, which came out of stealth less than two weeks ago!

    [...]

    10:53 They pressed the button live in the room. The reset affects everyone in the world, not just the DevDay attendees.

    Read it in full on Simon Willison →

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