Node.js HTTP Server

You can use the AI SDK in a Node.js HTTP server to generate text and stream it to the client.

Examples

The examples start a simple HTTP server that listens on port 8080. You can e.g. test it using curl:

curl -X POST http://localhost:8080

The examples use the Vercel AI Gateway. Ensure that your AI Gateway API key is set in the AI_GATEWAY_API_KEY environment variable.

Full example: github.com/vercel/ai/examples/node-http-server

UI Message Stream

You can use the pipeUIMessageStreamToResponse method to pipe the stream data to the server response.

index.ts

import { streamText } from 'ai';
import { createServer } from 'http';

createServer(async (req, res) => {
  const result = streamText({
    model: 'openai/gpt-4o',
    prompt: 'Invent a new holiday and describe its traditions.',
  });

  result.pipeUIMessageStreamToResponse(res);
}).listen(8080);

Sending Custom Data

createUIMessageStream and pipeUIMessageStreamToResponse can be used to send custom data to the client.

index.ts

import {
  createUIMessageStream,
  pipeUIMessageStreamToResponse,
  streamText,
} from 'ai';
import { createServer } from 'http';

createServer(async (req, res) => {
  switch (req.url) {
    case '/stream-data': {
      const stream = createUIMessageStream({
        execute: ({ writer }) => {
          // write some custom data
          writer.write({ type: 'start' });

          writer.write({
            type: 'data-custom',
            data: {
              custom: 'Hello, world!',
            },
          });

          const result = streamText({
            model: 'openai/gpt-4o',
            prompt: 'Invent a new holiday and describe its traditions.',
          });

          writer.merge(
            result.toUIMessageStream({
              sendStart: false,
              onError: error => {
                // Error messages are masked by default for security reasons.
                // If you want to expose the error message to the client, you can do so here:
                return error instanceof Error ? error.message : String(error);
              },
            }),
          );
        },
      });

      pipeUIMessageStreamToResponse({ stream, response: res });

      break;
    }
  }
}).listen(8080);

Text Stream

You can send a text stream to the client using pipeTextStreamToResponse.

index.ts

import { streamText } from 'ai';
import { createServer } from 'http';

createServer(async (req, res) => {
  const result = streamText({
    model: 'openai/gpt-4o',
    prompt: 'Invent a new holiday and describe its traditions.',
  });

  result.pipeTextStreamToResponse(res);
}).listen(8080);

Troubleshooting

Streaming not working when proxied