Claude Sonnet 4.5

Claude Sonnet 4.5, released by Anthropic in September 2025, is marketed as the best coding model and the best model for agents. With a 200K token context window and 64K token output limit, it provides substantial capacity for complex, multi-turn interactions and lengthy code generation tasks.

The model achieves 77.2% on SWE-bench (82% with parallel compute capabilities), demonstrating exceptional software engineering abilities. It scores 100% on AIME when provided with Python access and 83.4% on GPQA Diamond (graduate-level science questions), showing strong performance across mathematics, science, and programming domains. Sonnet 4.5 has gained particular recognition for its exceptional frontend and UI code generation capabilities.

Priced at $3 per million input tokens and $15 per million output tokens, Claude Sonnet 4.5 offers competitive pricing for its capability level. Its combination of strong reasoning, excellent coding abilities, and reliable agentic behavior has made it a popular choice for developers building AI-powered applications, particularly those involving code generation, autonomous agents, and complex multi-step workflows.