Simon Willison’s Weblog

OpenAI Canvas gets a huge upgrade. Canvas is the ChatGPT feature where ChatGPT can open up a shared editing environment and collaborate with the user on creating a document or piece of code. Today it got a very significant upgrade, which as far as I can tell was announced exclusively by tweet:

Canvas update: today we’re rolling out a few highly-requested updates to canvas in ChatGPT.

✅ Canvas now works with OpenAI o1—Select o1 from the model picker and use the toolbox icon or the “/canvas” command

✅ Canvas can render HTML & React code

Here's a follow-up tweet with a video demo.

Talk about burying the lede! The ability to render HTML leapfrogs Canvas into being a direct competitor to Claude Artifacts, previously Anthropic's single most valuable exclusive consumer-facing feature.

Also similar to Artifacts: the HTML rendering feature in Canvas is almost entirely undocumented. It appears to be able to import additional libraries from a CDN - but which libraries? There's clearly some kind of optional build step used to compile React JSX to working code, but the details are opaque.

I got an error message, Build failed with 1 error: internal:user-component.js:10:17: ERROR: Expected "}" but found ":" - which I couldn't figure out how to fix, and neither could the Canvas "fix this bug" helper feature.

At the moment I'm finding I hit errors on almost everything I try with it:

This feature has so much potential. I use Artifacts on an almost daily basis to build useful interactive tools on demand to solve small problems for me - but it took quite some work for me to find the edges of that tool and figure out how best to apply it.