Claude 3.7 Sonnet
Anthropic's first hybrid reasoning model, blending fast answers with extended thinking
Claude 3.7 Sonnet, released by Anthropic in February 2025, is the company’s first hybrid reasoning model. A single model can answer normally like a standard chat model or switch into an extended thinking mode where it works through a problem step by step before responding, and developers can control how much thinking budget the model uses through the API. This design let Anthropic ship one model that covers both quick everyday questions and harder math, coding, and logic problems, instead of maintaining separate fast and reasoning-focused models. It kept the same 200,000 token context window and $3/$15 per million token pricing as Claude 3.5 Sonnet, and it launched alongside Claude Code, Anthropic’s command-line coding agent, which used 3.7 Sonnet as its default model.