Claude 4 Sonnet is a leaner model, with improvements built on Anthropic's Claude 3.7 Sonnet model. The 3.7 model often had problems with overeagerness and sometimes did more than the person asked it to do, Amodei said. While it's a less resource-intensive model, it still performs well, he said.

Free, Pro, Max, Team, and Enterprise Claude plans can access Claude Sonnet 4 and Opus 4 now, with an extended thinking mode in beta.

During its inaugural developer conference, Anthropic launched two new AI models the startup claims are among the industry's best, at least in terms of how they score on popular benchmarks.