tech
January 9, 2026
Claude Sonnet 4.5
Hybrid reasoning model with superior intelligence for agents, and 200K context window
TL;DR
- Sonnet 4.5 is a hybrid reasoning model designed for agents, coding, and computer use, offering superior intelligence and accuracy.
- It shows significant improvements over previous versions, particularly in coding, content generation, data analysis, and planning.
- The model supports up to 64K output tokens and excels in various use cases including long-running agents, code generation, cybersecurity, financial analysis, research, and content creation.
- Sonnet 4.5 offers near-instant responses or visible extended, step-by-step thinking, allowing fine-grained control over the model's thinking process.
- It is available for general use on Claude.ai and for developers via the Claude Developer Platform, Amazon Bedrock, Google Cloud's Vertex AI, and Microsoft Foundry.
- Pricing starts at $3 per million input tokens and $15 per million output tokens, with potential cost savings through prompt caching and batch processing.
- Extensive testing and evaluation have been conducted to ensure safety, security, and reliability, with specific mention of improved performance in areas like vulnerability patching, code editing accuracy, and autonomous coding.
- Sonnet 4.5 is recommended for AI applications needing a balance of advanced capabilities and practical throughput, such as customer-facing agents and production coding workflows.
- Extended thinking mode is available for tasks where performance and accuracy are more critical than latency, enhancing response quality for complex reasoning and research.