Anthropic SDK

https://api.modrouter.online/anthropic

import os
from anthropic import Anthropic

base_url = os.environ["MODROUTER_BASE_URL"].rstrip("/")
api_key = os.environ["MODROUTER_API_KEY"]

client = Anthropic(
    base_url=f"{base_url}/anthropic",
    api_key=api_key,
)

message = client.messages.create(
    model="anthropic/claude-sonnet-4-5",
    max_tokens=512,
    messages=[{"role": "user", "content": "Hello"}],
)

print(message.content[0].text)

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

const baseURL = process.env.MODROUTER_BASE_URL.replace(/\/$/, "");
const apiKey = process.env.MODROUTER_API_KEY;

const client = new Anthropic({
  baseURL: `${baseURL}/anthropic`,
  apiKey,
});

const message = await client.messages.create({
  model: "anthropic/claude-sonnet-4-5",
  max_tokens: 512,
  messages: [{ role: "user", content: "Hello" }],
});

console.log(message.content[0].text);

message = client.messages.create(
    model="anthropic/claude-sonnet-4-5",
    max_tokens=512,
    messages=[{"role": "user", "content": "Hello"}],
    extra_headers={"x-bf-vk": os.environ["MODROUTER_API_KEY"]},
)