ai-sdk-local-fetch

Use Vercel AI SDK streamText directly on the client — no server required.

When users provide their own API key, you can skip the backend proxy entirely.
createLocalFetch returns a fetch-compatible function that routes AI SDK transport calls straight to a LanguageModel, without any HTTP round-trip.

Install

npm install ai-sdk-local-fetch

Usage

import { createLocalFetch } from "ai-sdk-local-fetch";
import { openai } from "@ai-sdk/openai";

const fetch = createLocalFetch({
  model: openai("gpt-5.2-chat"),
  system: "You are a helpful assistant.",
});

With @assistant-ui/react

import {
  AssistantChatTransport,
  useChatRuntime,
} from "@assistant-ui/react-ai-sdk";
import { createLocalFetch } from "ai-sdk-local-fetch";
import { openai } from "@ai-sdk/openai";

function Assistant({ apiKey }: { apiKey: string }) {
  const runtime = useChatRuntime({
    transport: new AssistantChatTransport({
      fetch: createLocalFetch({
        model: openai("gpt-5.2-chat", { apiKey }),
        system: "You are a helpful assistant.",
      }),
    }),
  });

  // ...
}