Reference · Snippet · typescript

Next.js streaming API route

Last updated Jul 17, 2026

nextjsstreamingopenai

import OpenAI from "openai";

export async function POST(req: Request) {
  const { prompt } = await req.json();
  const client = new OpenAI();

  const stream = await client.chat.completions.create({
    model: "gpt-4o-mini",
    stream: true,
    messages: [{ role: "user", content: prompt }],
  });

  const encoder = new TextEncoder();
  const readable = new ReadableStream({
    async start(controller) {
      for await (const chunk of stream) {
        const text = chunk.choices[0]?.delta?.content ?? "";
        if (text) controller.enqueue(encoder.encode(text));
      }
      controller.close();
    },
  });

  return new Response(readable, {
    headers: { "Content-Type": "text/plain; charset=utf-8" },
  });
}