Claude Sonnet 4.5

About Claude Sonnet 4.5

Claude Sonnet 4 is Anthropic's balanced next-generation model, delivering exceptional performance across coding, analysis, and creative tasks at accessible pricing. Building on the Sonnet tradition, it offers the best capability-to-cost ratio in Anthropic's lineup. Claude Sonnet 4 features an extended context window and demonstrates particularly strong performance on software development tasks. The model excels at understanding complex codebases, generating production-quality code, and debugging intricate issues. It supports vision capabilities for multimodal applications. For developers and enterprises seeking cutting-edge AI capability without flagship pricing, Claude Sonnet 4 offers excellent value. It's the recommended choice for most production use cases.

Model Specifications

💰 Real-World Cost Examples

Estimated monthly costs for common use cases

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🚀 Quick Start

Get started with Claude Sonnet 4.5 API

import anthropic

client = anthropic.Anthropic()

message = client.messages.create(
    model="anthropic/claude-4.5-sonnet-20250929",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Hello!"}
    ]
)
print(message.content[0].text)

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