Node.js

API reference

The official openai and @anthropic-ai/sdk packages work with Zukko without code changes — only the base URL and the key change. The examples below are ES modules (Node.js 18+, a .mjs file or "type": "module" in package.json).

SDK	Base URL	Key
OpenAI (`openai`)	`https://api.zukko.pro/v1`	`fetch_...`
Anthropic (`@anthropic-ai/sdk`)	`https://api.zukko.pro`	`fetch_...`

Keep the key in an environment variable:

bash

export ZUKKO_API_KEY="fetch_..."

1OpenAI SDK

bash

npm install openai

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.zukko.pro/v1",
  apiKey: process.env.ZUKKO_API_KEY,
});

const r = await client.chat.completions.create({
  model: "gpt-5.6-sol",
  messages: [{ role: "user", content: "Hello!" }],
});
console.log(r.choices[0].message.content);

Streaming

const stream = await client.chat.completions.create({
  model: "claude-sonnet-5",
  messages: [{ role: "user", content: "Write a haiku about code" }],
  stream: true,
});

for await (const chunk of stream) {
  if (chunk.choices.length > 0) {
    process.stdout.write(chunk.choices[0].delta?.content ?? "");
  } else if (chunk.usage) {
    console.log("\ntokens:", chunk.usage.prompt_tokens, "in,", chunk.usage.completion_tokens, "out");
  }
}

The chunk.choices.length check is required: Zukko enables stream_options.include_usage, and the last chunk of the stream comes with usage and an empty choices.

Request cost

const { data, response } = await client.chat.completions
  .create({ model: "glm-5.3-flash", messages: [{ role: "user", content: "Hello!" }] })
  .withResponse();

console.log(response.headers.get("x-zukko-cost-micros")); // microdollars
console.log(data.choices[0].message.content);

The header is present only on regular (non-streaming) responses.

2Anthropic SDK

bash

npm install @anthropic-ai/sdk

import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({
  baseURL: "https://api.zukko.pro",
  apiKey: process.env.ZUKKO_API_KEY,
});

const msg = await client.messages.create({
  model: "claude-sonnet-5",
  max_tokens: 1024,
  messages: [{ role: "user", content: "Hello!" }],
});
console.log(msg.content[0].text);

Base URL without /v1: the SDK appends /v1/messages itself.

Streaming

const stream = client.messages.stream({
  model: "claude-sonnet-5",
  max_tokens: 1024,
  messages: [{ role: "user", content: "Write a haiku about code" }],
});

stream.on("text", (text) => process.stdout.write(text));
const final = await stream.finalMessage();
console.log("\noutput tokens:", final.usage.output_tokens);

3If something is off

Error codes and what to do about them are in API errors. Stream formats are in Streaming.

Python

POST /v1/chat/completions