OpenUI and JSON-render are some other players in this space.
I’m building an agentic commerce chat that uses MCP-UI and want to start using these new implementations instead of MCP-UI but can’t wrap my head around how button on click and actions work? MCP-UI allows onClick events to work since you’re “hard coding” the UI from the get-go vs relying on AI generating undertemistic JSON and turning that into UI that might be different on every use.
When the user clicks the button, it invokes the server-side function. The callback fetches fresh data, updates state via reactive proxies, and the UI reflects it — all without triggering a new LLM turn.
So the UI is generated dynamically by the LLM, but the interactions are real server-side code, not just display. Forms work the same way — "await form.result" pauses execution until the user submits.
The article has a full walkthrough of the four data flow patterns (forms, live updates, streaming data, callbacks) with demos.
There’s definitely a lot of merit to this idea, and the gifs in the article look impressive. My strong opinion is that there’s a lot more to (good) UIs than what an LLM will ever be able to bring (happy to be proven wrong in a few years…), but for utilitarian and on-the-fly UIs there’s definitely a lot of promise
Markdown UI and my approach share the "markdown as the medium" insight, but they're fundamentally different bets:
Markdown UI is declarative — you embed predefined widget types in markdown. The LLM picks from a catalog. It's clean and safe, but limited to what the catalog supports.
My approach is code-based — the LLM writes executable TypeScript in markdown code fences, which runs on the server and can render any React UI. It also has server-side state, so the UI can do forms, callbacks, and streaming data — not just display widgets.
Using markdown as the transport layer is clever because every LLM already speaks it fluently. You're not teaching the model a new format, you're just giving existing behavior a runtime.
It embodies the whole idea of having data, code and presentation at the same place.
If you're open for contributions I already have an idea for cascading styles system in mind.
Maybe one day someone will invent a rounder wheel.
The wheel is what I would call, passé.
I’m building an agentic commerce chat that uses MCP-UI and want to start using these new implementations instead of MCP-UI but can’t wrap my head around how button on click and actions work? MCP-UI allows onClick events to work since you’re “hard coding” the UI from the get-go vs relying on AI generating undertemistic JSON and turning that into UI that might be different on every use.
So the UI is generated dynamically by the LLM, but the interactions are real server-side code, not just display. Forms work the same way — "await form.result" pauses execution until the user submits.
The article has a full walkthrough of the four data flow patterns (forms, live updates, streaming data, callbacks) with demos.
https://markdown-ui.com/
Markdown UI is declarative — you embed predefined widget types in markdown. The LLM picks from a catalog. It's clean and safe, but limited to what the catalog supports.
My approach is code-based — the LLM writes executable TypeScript in markdown code fences, which runs on the server and can render any React UI. It also has server-side state, so the UI can do forms, callbacks, and streaming data — not just display widgets.