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

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.

Claude Opus 4 is the world’s best coding model, Anthropic said. The company also released a safety report for the hybrid reasoning models.