# Quick Start

You want a streaming chat in your app. TanStack AI streams from a server route. The hook for your framework renders the tokens.

> [!TIP]
> If you do not want a key per provider, [OpenRouter](../adapters/openrouter) gives you 300+ models with one API key.

React Native or Expo needs an absolute server URL and an XHR transport. See [Quick Start: React Native](./quick-start-react-native).

No UI: see [Quick Start: Server Only](./quick-start-server).

## 1. Install

```sh
npm i @tanstack/ai @tanstack/ai-preact @tanstack/ai-openai
```

## 2. Stream from the server

Call `chat()`. Then wrap the result with `toServerSentEventsResponse`.

```typescript
import {
  chat,
  chatParamsFromRequest,
  toServerSentEventsResponse,
} from "@tanstack/ai";
import { openaiText } from "@tanstack/ai-openai";

export async function POST(request: Request) {
  const { messages, threadId, runId } = await chatParamsFromRequest(request);

  const stream = chat({
    adapter: openaiText("gpt-5.6"),
    messages,
    threadId,
    runId,
  });

  return toServerSentEventsResponse(stream);
}
```

This works with TanStack Start, Next.js, SvelteKit, Hono, and any host that returns a Web `Response`.

If your server is Node streams (Express), see [Quick Start: Server Only](./quick-start-server).

Put the API key on the server:

```bash
OPENAI_API_KEY=your-openai-api-key
```

The adapter reads `OPENAI_API_KEY` at runtime. Do not send this key to the browser.

If you do not want a server key, see [Bring Your Own Key](../advanced/byok).

## 3. Render the chat

Call `useChat` from `@tanstack/ai-preact`. Hold the composer text with `useState` from `preact/hooks`.

```tsx ignore
import { useState } from "preact/hooks";
import { useChat, fetchServerSentEvents } from "@tanstack/ai-preact";

export function Chat() {
  const [input, setInput] = useState("");
  const { messages, sendMessage, isLoading, stop } = useChat({
    connection: fetchServerSentEvents("/api/chat"),
  });

  return (
    <>
      {messages.map((message) => (
        <div key={message.id}>
          {message.parts.map((part, index) =>
            part.type === "text" ? <p key={index}>{part.content}</p> : null,
          )}
        </div>
      ))}
      <form
        onSubmit={(event) => {
          event.preventDefault();
          if (input.trim() === "") {
            return;
          }
          sendMessage(input);
          setInput("");
        }}
      >
        <input
          value={input}
          onInput={(event) => setInput(event.currentTarget.value)}
        />
        {isLoading ? (
          <button type="button" onClick={stop}>
            Stop
          </button>
        ) : (
          <button type="submit">Send</button>
        )}
      </form>
    </>
  );
}
```

See the [Preact API](../api/ai-preact).

Send a message. Tokens show up in the UI.

## Later

- [Tools](../tools/tools) for function calling
- [Streaming](../chat/streaming) for cancel, callbacks, and transports
- [Adapters](../adapters/openai) for other providers