Claude Sonnet 4.5

Claude Sonnet 4.5 is Anthropic's flagship model in the Sonnet family, representing the company's most capable offering for complex reasoning and multimodal tasks. As a proprietary model developed by Anthropic, it sits at the top tier of the Claude model lineup, designed for demanding applications that require sophisticated understanding and generation capabilities. The model supports both text and image inputs with a 200K token context window, enabling processing of lengthy documents and detailed visual content. It includes tool calling functionality and maintains a knowledge cutoff of January 1, 2025. The model excels at chat completion and code generation tasks, handling complex conversations and programming challenges with multimodal understanding. Claude Sonnet 4.5 competes directly with other flagship models like GPT-5.4 and Gemini 3.1 Pro in the current landscape. Organizations typically deploy it for applications requiring the highest level of reasoning capability, complex document analysis with visual elements, and sophisticated coding assistance where accuracy and context retention are critical.