Anthropic says Claude Opus 4 is its most powerful model and the best coding model in the world, while Sonnet 4 is replacing Sonnet 3.7 in the chatbot.

A third-party research institute Anthropic partnered with to test Claude Opus 4 recommended against deploying an early version because it tends to "scheme."

Anthroic Claude 3.5 and 3.7 have been the leading models for coding. They were being threatened by Google Gemini 2.5 but now Claude 4 Sonnet and Opus are out.