Since the JSON extras API is a little hard to explain without an example I also had Fable 5 and GPT-5.5 collaborate on this custom API explorer tool for trying out the new feature tools.simonwillison.net/data…
Author Simon Willison built a custom API explorer to demonstrate the JSON extras…
Brief
Simon Willison released a custom API explorer (tools.simonwillison.net/data) on June 11, 2026 to demonstrate the new JSON extras API. He had Fable 5 and GPT-5.5 collaborate on the demo so users can interactively try the JSON extras feature and see concrete examples of how it works.
Why it matters
Author Simon Willison built a custom API explorer to demonstrate the JSON extras API and make the feature easier to understand.
Key details
- He collaborated with two models—Fable 5 and GPT-5.5—to create the tool, published June 11, 2026.
- The demo is available at tools.simonwillison.net/data for interactive testing of the new JSON extras feature.