# Node.js / TypeScript
npm install @claude-ai/sdk

# Python
pip install anthropic

# Set environment variable (recommended)
export ANTHROPIC_API_KEY="sk-ant-api03-..."

# Or add to .env file
echo 'ANTHROPIC_API_KEY=sk-ant-api03-...' >> .env

import Anthropic from '@claude-ai/sdk';

const client = new Anthropic(); // reads ANTHROPIC_API_KEY from env

const message = await client.messages.create({
  model: 'claude-sonnet-4-20250514',
  max_tokens: 64,
  messages: [{ role: 'user', content: 'Say "connected" in one word.' }],
});
console.log(message.content[0].text); // "Connected"

import anthropic

client = anthropic.Anthropic()  # reads ANTHROPIC_API_KEY from env

message = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=64,
    messages=[{"role": "user", "content": "Say 'connected' in one word."}],
)
print(message.content[0].text)  # "Connected"

import Anthropic from '@claude-ai/sdk';

// Default: reads ANTHROPIC_API_KEY from environment
const client = new Anthropic();

// Explicit key (for testing only — don't hardcode in production)
const client = new Anthropic({ apiKey: 'sk-ant-api03-...' });

// Custom base URL (for proxies or Vertex AI)
const client = new Anthropic({
  baseURL: 'https://your-proxy.example.com',
});

import anthropic

# Default: reads ANTHROPIC_API_KEY from environment
client = anthropic.Anthropic()

# Explicit key
client = anthropic.Anthropic(api_key="sk-ant-api03-...")

# Async client
client = anthropic.AsyncAnthropic()