OpenAI DevDay 2026 live blog
- ID
- 29879
- Status
- summarized
- Published
- 29 Sep 2026, 11:55 PM
- Fetched
- 30 Sep 2026, 6:20 AM
- Provider
- Simon Willison
- Category
- developer-ai
- Original URL
- https://simonwillison.net/2026/Sep/29/openai-devday-2026-live-blog/
- Source URL
- https://simonwillison.net/atom/everything/
Summary
- Score
- 3.0
- Created
- 30 Sep 2026, 6:21 AM
- Tags
- Audience
- developersvibe_codersai_ml_learners
What happened
Simon Willison's post is the opening entry of a live blog from OpenAI DevDay 2026 at Fort Mason, San Francisco, published 29 September 2026 — written before the keynote began, so it contains no product announcements. The only concrete technical detail is his own tooling: he vibe-coded a photo-upload system for the live blog on his phone en route to the venue, started on Codex Cloud, hit problems, and switched to Claude Code for web. The page's "more recent articles" links reference a prior post titled "Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war" (22 September 2026), but no DevDay content is in this text.
Why it matters
There is nothing here to act on yet: no models, prices, limits, or APIs are named, so no decision about your stack can be made from this item. The one usable signal is a small workflow data point — a developer trying to build on a phone abandoned Codex Cloud mid-task and finished on Claude Code for web, which is worth noting if you rely on either for mobile or quick-turnaround work. Treat the DevDay announcements themselves as unread until the keynote text exists; the adjacent headline about a September 2026 price war across Claude Opus 5.5, GPT-6 Sol and GPT-6 Luna suggests pricing is moving fast, but that is a separate article, not this one.
Discussion angle
Which coding agent actually survives a real deadline: Codex Cloud failed for Willison mid-build on mobile and Claude Code for web picked it up — ask the room where they've hit the same swap and what triggered it.