"Chatbots that reply with Markdown are so 2023. The future is Generative UI."

Why return markdown text when you can return interactive React Components?

The Vercel AI SDK allows the LLM to call functions that return Server Components, which are then streamed to the client via a readable stream.
We call this Generative UI. The AI doesn't just talk; it paints the screen.

02. Generative UI

Standard AI: User asks "Stock price of AAPL". AI replies "It is $150".
Generative UI: User asks "Stock price of AAPL". AI replies with a stream that hydrates into a <StockChart ticker="AAPL" /> component.

💬 Text Stream

"Sure, I can help with that. Here is the data..."

⚛️ Component Stream

<Suspense><FlightCard /></Suspense>

03. Tool Calling (The Magic)

The secret sauce is Tool Calling. You define tools (functions) that the AI can "call". Next.js intercepts these calls on the server and renders the corresponding component.

// Server Action (actions.tsx)
export async function submitUserMessage(input: string) {
  const ui = await render({
    model: 'gpt-4-turbo',
    messages: [{ role: 'user', content: input }],
    tools: {
      get_weather: {
        description: 'Get the weather',
        parameters: z.object({ location: z.string() }),
        render: async function* ({ location }) {
          yield <Spinner /> // 1. Show loading state
          const weather = await fetchWeather(location)
          return <WeatherCard data={weather} /> // 2. Stream final UI
        }
      }
    }
  })
  return { ui }
}

04. Structured Outputs (JSON)

Sometimes you don't need UI; you need data. The SDK ensures strict JSON output using Zod schemas. No more "I'm sorry but as an AI..." prefixes ruining your `JSON.parse()`.

// generateObject

const { object } = await generateObject({
  model: openai('gpt-4-json'),
  schema: z.object({
    recipe: z.object({
      name: z.string(),
      ingredients: z.array(z.string())
    })
  }),
  prompt: 'Generate a lasagna recipe'
})

// Result is fully typed:
console.log(object.recipe.name); // 'Classic Lasagna'

05. Share the Future

"Text is the bottleneck of AI. The future is Generative UI. Let the LLM build your interface on the fly with Vercel AI SDK. #AI #React #Nextjs"

Twitter / X

The Takeaway

The interface is no longer static. It is fluid. It is generated for you, right now.

06. AI Chat Simulator

Type "Show me AAPL stock" to see the AI generate a UI component instead of text.

Concept Component Streaming

The simulator below mocks the server response delay. Notice the "IsTyping" indicator vs the final UI render.

⚡ Interactive Playground

import React, { useState } from 'react';

// ----------------------------------------------------
// 🤖 GENERATIVE UI SIMULATOR
// ----------------------------------------------------

export default function GenerativeChat() {
  const [messages, setMessages] = useState([
      { id: 1, role: 'assistant', content: 'Hello! I can render UI. Ask me for a stock price or flight info.' }
  ]);
  const [input, setInput] = useState('');
  const [isTyping, setIsTyping] = useState(false);

  const handleSubmit = (e) => {
    e.preventDefault();
    if(!input) return;
    
    // Optimistic Update
    const userMsg = { id: Date.now(), role: 'user', content: input };
    setMessages(prev => [...prev, userMsg]);
    setInput('');
    setIsTyping(true);

    // Simulate AI Logic & Tool Calling
    setTimeout(() => {
        setIsTyping(false);
        let aiMsg;

        if (userMsg.content.toLowerCase().includes('stock')) {
             aiMsg = { 
                 id: Date.now() + 1, 
                 role: 'assistant', 
                 component: <StockCard /> // 👈 Generative UI
             };
        } else if (userMsg.content.toLowerCase().includes('flight')) {
             aiMsg = { 
                 id: Date.now() + 1, 
                 role: 'assistant', 
                 component: <FlightCard /> // 👈 Generative UI
             };
        } else {
             aiMsg = { 
                 id: Date.now() + 1, 
                 role: 'assistant', 
                 content: "I didn't catch that. Try asking for 'stock' or 'flight' to trigger the component generator." 
             };
        }
        setMessages(prev => [...prev, aiMsg]);

    }, 1500);
  };

  return (
    <div className="bg-white dark:bg-[#111] text-gray-900 dark:text-gray-200 border border-gray-200 dark:border-gray-800 rounded-2xl overflow-hidden shadow-2xl flex flex-col h-[600px]">
      
      {/* Chat Messages */}
      <div className="flex-1 overflow-y-auto p-6 space-y-6 bg-gray-50 dark:bg-black/50">
           {messages.map(m => (
               <div key={m.id} className={`flex ${m.role === 'user' ? 'justify-end' : 'justify-start'}`}>
                   
                   {m.role === 'assistant' ? (
                       <div className="max-w-[80%]">
                           <div className="text-xs font-bold text-indigo-500 mb-1">AI</div>
                           {m.component ? (
                               // RENDER GENERATIVE UI
                               <div className="animate-in zoom-in-95 duration-500">
                                   {m.component}
                               </div>
                           ) : (
                               <div className="bg-white dark:bg-zinc-800 p-4 rounded-2xl rounded-tl-none shadow-sm text-sm border border-gray-100 dark:border-gray-700">
                                   {m.content}
                               </div>
                           )}
                       </div>
                   ) : (
                       <div className="max-w-[80%]">
                           <div className="bg-blue-600 text-white p-3 rounded-2xl rounded-tr-none text-sm shadow-md">
                               {m.content}
                           </div>
                       </div>
                   )}
               </div>
           ))}
           
           {isTyping && (
               <div className="flex justify-start">
                   <div className="bg-gray-200 dark:bg-gray-800 p-3 rounded-2xl rounded-tl-none flex gap-1 items-center">
                       <span className="w-2 h-2 bg-gray-500 rounded-full animate-bounce"></span>
                       <span className="w-2 h-2 bg-gray-500 rounded-full animate-bounce delay-75"></span>
                       <span className="w-2 h-2 bg-gray-500 rounded-full animate-bounce delay-150"></span>
                   </div>
               </div>
           )}
      </div>

      {/* Input */}
      <form onSubmit={handleSubmit} className="p-4 bg-white dark:bg-[#111] border-t border-gray-200 dark:border-gray-800 flex gap-2">
          <input 
             className="flex-1 bg-gray-100 dark:bg-zinc-900 border-0 rounded-xl px-4 py-3 focus:ring-2 ring-indigo-500 outline-none"
             placeholder="Ask for stock or flight info..."
             value={input}
             onChange={e => setInput(e.target.value)}
          />
          <button type="submit" className="bg-indigo-600 hover:bg-indigo-700 text-white p-3 rounded-xl transition-colors">
              <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 19l9 2-9-18-9 18 9-2zm0 0v-8" /></svg>
          </button>
      </form>
    </div>
  );
}

// --- DUMMY GENERATIVE COMPONENTS ---

function StockCard() {
    return (
        <div className="bg-white dark:bg-zinc-900 border border-gray-200 dark:border-gray-700 rounded-xl p-4 shadow-lg w-64">
             <div className="flex justify-between items-start mb-4">
                 <div>
                     <h3 className="font-bold text-lg">AAPL</h3>
                     <p className="text-gray-500 text-xs">Apple Inc.</p>
                 </div>
                 <div className="text-green-500 font-bold bg-green-100 dark:bg-green-900/30 px-2 py-1 rounded text-xs">+1.24%</div>
             </div>
             <div className="text-3xl font-bold mb-4">$184.22</div>
             {/* Fake Chart */}
             <div className="h-16 flex items-end justify-between gap-1">
                 {[40, 60, 45, 70, 65, 85, 80].map((h, i) => (
                     <div key={i} className="w-full bg-green-500/20 rounded-sm" style={{ height: `${h}%` }}></div>
                 ))}
             </div>
             <button className="w-full mt-4 bg-gray-900 dark:bg-white text-white dark:text-black py-2 rounded-lg text-xs font-bold hover:opacity-90">Buy Stock</button>
        </div>
    )
}

function FlightCard() {
    return (
        <div className="bg-white dark:bg-zinc-900 border border-gray-200 dark:border-gray-700 rounded-xl p-0 shadow-lg w-72 overflow-hidden">
             <div className="bg-indigo-600 p-4 text-white">
                 <div className="flex justify-between text-xs font-bold opacity-80 mb-1">
                     <span>SFO</span>
                     <span>JFK</span>
                 </div>
                 <div className="flex justify-between text-2xl font-bold">
                     <span>10:30</span>
                     <span>18:45</span>
                 </div>
             </div>
             <div className="p-4 space-y-3">
                 <div className="flex justify-between text-sm border-b border-gray-100 dark:border-gray-800 pb-2">
                     <span className="text-gray-500">Date</span>
                     <span className="font-bold">May 24</span>
                 </div>
                 <div className="flex justify-between text-sm border-b border-gray-100 dark:border-gray-800 pb-2">
                     <span className="text-gray-500">Flight</span>
                     <span className="font-bold">UA 421</span>
                 </div>
                 <button className="w-full bg-indigo-100 dark:bg-indigo-900/30 text-indigo-700 dark:text-indigo-300 py-2 rounded-lg text-xs font-bold hover:bg-indigo-200 transition-colors">Select Flight</button>
             </div>
        </div>
    )
}

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