Node.js

What it is

JavaScript on the server. Single-threaded event loop, non-blocking I/O — ideal for orchestrating LLM calls, database writes and webhook fan-out without thread overhead.

How Vaaani uses it

• Streaming LLM responses to clients via SSE / WebSockets
• Background workers that drain a queue of AI tasks
• BFF (backend-for-frontend) layers in front of Python AI services
• Edge functions on Cloudflare Workers / Vercel Edge

Why it makes the cut

Most AI workers are 95% waiting on a network call. Node's event loop makes that waiting cheap. Python can do this too — but Node feels native.

Sample code

import { ChatOpenAI } from "@langchain/openai";

const model = new ChatOpenAI({ model: "gpt-4o" });
const stream = await model.stream("Hello");

for await (const chunk of stream) {
  process.stdout.write(chunk.content);
}