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Prerequisite: You need an AI Gateway endpoint before continuing. Create one using the dashboard quickstart or follow the manual setup guide.
TanStack AI is a type-safe library for building AI applications with React, Solid, and other frameworks. It works seamlessly with the ngrok AI Gateway through its OpenAI adapter.

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Installation

npm install @tanstack/ai @tanstack/ai-openai

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Basic usage

Configure the OpenAI adapter to use your AI Gateway endpoint: 
import { chat } from "@tanstack/ai";
import { openai } from "@tanstack/ai-openai";

const adapter = openai({
  baseURL: "https://your-ai-subdomain.ngrok.app/v1",
  apiKey: process.env.OPENAI_API_KEY,
});

const stream = chat({
  adapter,
  messages: [{ role: "user", content: "Hello!" }],
  model: "gpt-4o",
});

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Streaming responses

TanStack AI is built for streaming. Process chunks as they arrive: 
import { chat } from "@tanstack/ai";
import { openai } from "@tanstack/ai-openai";

const adapter = openai({
  baseURL: "https://your-ai-subdomain.ngrok.app/v1",
  apiKey: process.env.OPENAI_API_KEY,
});

const stream = chat({
  adapter,
  messages: [{ role: "user", content: "Write a poem about AI gateways." }],
  model: "gpt-4o",
});

for await (const chunk of stream) {
  // Process each chunk as it arrives
  console.log(chunk);
}

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API route handler

Build API endpoints that stream responses:
app/api/chat/route.ts
import { chat, toStreamResponse } from "@tanstack/ai";
import { openai } from "@tanstack/ai-openai";

const adapter = openai({
  baseURL: "https://your-ai-subdomain.ngrok.app/v1",
  apiKey: process.env.OPENAI_API_KEY,
});

export async function POST(request: Request) {
  const { messages } = await request.json();

  const stream = chat({
    adapter,
    messages,
    model: "gpt-4o",
  });

  return toStreamResponse(stream);
}

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Using different providers

The AI Gateway routes based on the model name. Use provider prefixes to target specific providers: 
import { chat } from "@tanstack/ai";
import { openai } from "@tanstack/ai-openai";

const gateway = openai({
  baseURL: "https://your-ai-subdomain.ngrok.app/v1",
  apiKey: "unused", // Gateway handles auth
});

// Use different providers through the same gateway
const openaiStream = chat({ adapter: gateway, model: "openai:gpt-4o", messages });
const anthropicStream = chat({ adapter: gateway, model: "anthropic:claude-3-5-sonnet-latest", messages });

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Automatic model selection

Let the gateway choose the best model with ngrok/auto: 
import { chat } from "@tanstack/ai";
import { openai } from "@tanstack/ai-openai";

const gateway = openai({
  baseURL: "https://your-ai-subdomain.ngrok.app/v1",
  apiKey: "unused",
});

const stream = chat({
  adapter: gateway,
  model: "ngrok/auto", // Gateway selects based on your strategy
  messages: [{ role: "user", content: "Explain quantum computing" }],
});
Configure your selection strategy in the Traffic Policy:
traffic-policy.yaml
on_http_request:
  - type: ai-gateway
    config:
      providers:
        - id: openai
          api_keys:
            - value: ${secrets.get('openai', 'api-key')}
        - id: anthropic
          api_keys:
            - value: ${secrets.get('anthropic', 'api-key')}
      model_selection:
        strategy:
          - "ai.models.sortBy(m, m.pricing.input)" # Cheapest first

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Tool calling

The AI Gateway supports function/tool calling: 
import { chat, toolDefinition } from "@tanstack/ai";
import { openai } from "@tanstack/ai-openai";
import { z } from "zod";

const adapter = openai({
  baseURL: "https://your-ai-subdomain.ngrok.app/v1",
  apiKey: process.env.OPENAI_API_KEY,
});

const getWeatherDef = toolDefinition({
  name: "get_weather",
  description: "Get the current weather",
  inputSchema: z.object({
    location: z.string().describe("The location to get weather for"),
  }),
});

const getWeather = getWeatherDef.server(async ({ location }) => {
  return { temperature: 72, conditions: "sunny" };
});

const stream = chat({
  adapter,
  messages: [{ role: "user", content: "What's the weather in San Francisco?" }],
  model: "gpt-4o",
  tools: [getWeather],
});

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Provider options

Pass provider-specific options for fine-grained control: 
import { chat } from "@tanstack/ai";
import { openai } from "@tanstack/ai-openai";

const adapter = openai({
  baseURL: "https://your-ai-subdomain.ngrok.app/v1",
  apiKey: process.env.OPENAI_API_KEY,
});

const stream = chat({
  adapter,
  messages,
  model: "gpt-4o",
  providerOptions: {
    temperature: 0.7,
    maxTokens: 1000,
    topP: 0.9,
    frequencyPenalty: 0.5,
    presencePenalty: 0.5,
  },
});

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React integration

Use TanStack AI with React for building chat interfaces:
app/page.tsx
"use client";

import { useChat } from "@tanstack/ai-react";

export default function Chat() {
  const { messages, input, handleInputChange, handleSubmit } = useChat({
    api: "/api/chat",
  });

  return (
    <div>
      {messages.map((m) => (
        <div key={m.id}>
          {m.role}: {m.content}
        </div>
      ))}
      <form onSubmit={handleSubmit}>
        <input value={input} onChange={handleInputChange} />
        <button type="submit">Send</button>
      </form>
    </div>
  );
}

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Environment variables

Set up your environment:
.env.local
# Your AI Gateway endpoint
AI_GATEWAY_URL=https://your-ai-subdomain.ngrok.app/v1

# Optional: API key if using passthrough mode
OPENAI_API_KEY=sk-...

import { openai } from "@tanstack/ai-openai";

const adapter = openai({
  baseURL: process.env.AI_GATEWAY_URL,
  apiKey: process.env.OPENAI_API_KEY ?? "unused",
});

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Next steps