Anthropic SDK Compatibility

OneRouter AI provides a compatibility API that allows you to use the Anthropic SDK with OneRouter AI models. This is useful if you are already using the Anthropic SDK and want to switch to OneRouter AI models.

Quick Start Guide

This guide demonstrates how to use the Anthropic SDK with the OneRouter AI models step by step.

1. Install the Anthropic SDK

pip install anthropic

2. Initialize the Client

The Anthropic SDKs are designed to pull the API key and base URL from the environmental variables: ANTHROPIC_API_KEY and ANTHROPIC_BASE_URL. Also, you can supply the parameters to the Anthropic client when initializing it.

• Using Environment Variables

export ANTHROPIC_BASE_URL="https://llm.onerouter.pro"
export ANTHROPIC_API_KEY="<<Your OneRouter API Key>>"

• Set the parameters while initializing the Anthropic client

Python

import anthropic

client = anthropic.Anthropic(
    base_url="https://llm.onerouter.pro",
    api_key="<<Your OneRouter API Key>>"
)

message = client.messages.create(
    model="claude-sonnet-4@20250514",
    max_tokens=1000,
    temperature=1,
    system=[
        {
            "type": "text",
            "text": "You are a world-class poet. Respond only with short poems."
        }
    ],
    messages=[
        {
            "role": "user",
            "content": [
                {
                    "type": "text",
                    "text": "Why is the ocean salty?"
                }
            ]
        }
    ]
)

print(message.content)