Vercel AI SDK — Build AI Apps in TypeScript

Core Functions

generateText — Simple Completion

const { text } = await generateText({
  model: anthropic("claude-sonnet-4-20250514"),
  prompt: "Write a haiku about coding",
});

streamText — Streaming Response

const result = streamText({
  model: anthropic("claude-sonnet-4-20250514"),
  messages: [{ role: "user", content: "Tell me a story" }],
});

for await (const chunk of result.textStream) {
  process.stdout.write(chunk);
}

generateObject — Structured Output

import { z } from "zod";

const { object } = await generateObject({
  model: anthropic("claude-sonnet-4-20250514"),
  schema: z.object({
    recipe: z.string(),
    ingredients: z.array(z.string()),
    steps: z.array(z.string()),
  }),
  prompt: "Generate a recipe for chocolate cake",
});
// object.recipe, object.ingredients, object.steps — fully typed!

Tool Use

const result = await generateText({
  model: anthropic("claude-sonnet-4-20250514"),
  tools: {
    getWeather: {
      description: "Get weather for a location",
      parameters: z.object({ city: z.string() }),
      execute: async ({ city }) => ({ temp: 22, condition: "sunny" }),
    },
  },
  prompt: "What is the weather in Tokyo?",
});

React Hooks (useChat)

"use client";
import { useChat } from "ai/react";

export default function Chat() {
  const { messages, input, handleInputChange, handleSubmit } = useChat();

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

Provider Adapters

Key Stats

• 12,000+ GitHub stars
• By Vercel
• 20+ provider adapters
• Streaming, tools, structured output
• React/Svelte/Vue hooks

FAQ

Q: What is Vercel AI SDK? A: A TypeScript SDK providing a unified API for building AI features with streaming, tool use, and structured output across 20+ model providers.

Q: Is it free? A: Yes, open-source under Apache 2.0. You provide your own API keys.

Q: Do I need Next.js? A: No, the core SDK works with any Node.js project. The React hooks work with any React app.