Using Claude Sonnet 4.5 on Anthropic

Quick Start

1. 1
   Create an account at Anthropic and generate an API key.
2. 2
   Use the Anthropic SDK or REST API to call claude-sonnet-4-5 — see the documentation for request format.
3. 3
   You'll be billed $3.00/1M input, $15.00/1M output tokens. See full pricing.

Code Examples

import anthropic

client = anthropic.Anthropic()  # reads ANTHROPIC_API_KEY from env
message = client.messages.create(
    model="claude-sonnet-4-5",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello"}]
)
print(message.content[0].text)

About Anthropic

Creator of Claude AI models, accessed via the Anthropic API and the Anthropic Console (console.anthropic.com). The Console hosts the Workbench prompt playground, API keys, usage analytics, and team billing.

Anthropic is a safety-focused AI research company and creator of the Claude model family, offering API access through the Anthropic Console for text generation, analysis, and coding tasks.

Pricing on Anthropic

Capabilities

About Claude Sonnet 4.5

Claude Sonnet 4.5 is Anthropic's Claude 4.5 model with multimodal text and image input and an optional reasoning mode. It offers a 200K-token context window and scores 86 on MMLU PRO.