CORS Chat
- ID
- 14567
- Status
- summarized
- Published
- 15 Aug 2026, 10:49 PM
- Fetched
- 16 Aug 2026, 9:53 AM
- Provider
- Simon Willison
- Category
- developer-ai
- Original URL
- https://simonwillison.net/2026/Aug/15/cors-chat/
- Source URL
- https://simonwillison.net/atom/everything/
Summary
- Score
- 6.5
- Created
- 16 Aug 2026, 9:53 AM
- Tags
- Audience
- developersvibe_codersai_agent_users
What happened
Simon Willison built CORS Chat, a browser-based tool for chatting directly with any OpenAI Responses-compatible API endpoint that supports CORS headers. He used it to test Qwen 3.8 27B running in LM Studio on an M5 MacBook Pro and an NVIDIA DGX Spark, with conversations persisted locally and exportable as JSON. It also progressively renders SVG images while tokens are still streaming.
Why it matters
If you run local models via LM Studio (with the --cors flag) or use OpenRouter, this gives you a zero-backend, browser-only chat UI for testing endpoints—useful for quick model evaluation without spinning up a separate frontend. The progressive SVG rendering detail is worth noting if you build streaming UIs.
Discussion angle
How useful is a browser-only CORS-based chat UI versus just using LM Studio's built-in interface or a quick script—what testing scenarios does it actually solve better?