OpenAI SDK (TypeScript)

Install

Bash

npm install openai

A non-streaming completion

TypeScript

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.lowrouter.ai/v1",
  apiKey: process.env.LOWROUTER_API_KEY,
});

const response = await client.chat.completions.create({
  model: "auto/mistralai/mistral-large-2512",
  messages: [
    { role: "user", content: "In one sentence, what is a vector database?" },
  ],
});

console.log(response.choices[0].message.content);

A streaming completion

TypeScript

const stream = await client.chat.completions.create({
  model: "auto/mistralai/mistral-large-2512",
  stream: true,
  messages: [{ role: "user", content: "Count to 5 slowly" }],
});

for await (const chunk of stream) {
  const delta = chunk.choices[0]?.delta?.content;
  if (delta) process.stdout.write(delta);
}

Keep the ?. on choices[0]. The last frame before [DONE] has an empty choices array: it carries usage (with cost, currency and remaining_balance) and lowrouter_metadata, the per-request receipt, and it is sent whether or not you set stream_options.include_usage (see request parameters). Read chunk.usage and (chunk as any).lowrouter_metadata from that frame when you want the cost of the streamed request.

Reading the eco metadata

The TypeScript types do not include LowRouter’s extra fields. Cast or narrow when you read them:

TypeScript

type LowRouterMeta = {
  provider: string;
  region: string;
  energy_wh: number;
  carbon_gco2e: number;
  carbon_intensity_gco2_per_kwh: number;
  estimation_methodology?: string; // absent when no estimate was made
  routing_mode: string;
  routing_reason: string;
  fallback_occurred: boolean;
  providers_attempted: string[];
};

const r = await client.chat.completions.create({ /* ... */ });
const meta = (r as unknown as { lowrouter_metadata?: LowRouterMeta })
  .lowrouter_metadata;
if (meta) {
  console.log(
    `${meta.carbon_gco2e.toFixed(4)} gCO2e via ${meta.provider} (${meta.region})`,
  );
}

Pinning a region

There is no separate route field. Pin a region by appending a UN/LOCODE as the fourth segment of the model ID ({provider}/{creator}/{model}/{locode}); omit it to use the default region:

TypeScript

const response = await client.chat.completions.create({
  model: "aws-bedrock/mistralai/ministral-3-3b-instruct/br-gru",
  messages: [{ role: "user", content: "hi" }],
});

Browser usage

The OpenAI SDK warns against running with an API key in the browser because the key is then exposed to every page visitor. The same applies to LowRouter: keep your LOWROUTER_API_KEY server-side and proxy requests from a backend you control. If you need a signed, short-lived token for a browser client, mint it from a server-side endpoint.