Anthropic releases Claude Opus 4 and Claude Sonnet 4

Anthropic released Claude Opus 4, which it called its most capable coding model, and Claude Sonnet 4 on 22 May 2025. Both offered a choice between fast replies and extended reasoning, and could search the web while reasoning. Claude Code reached general availability the same day.

Why it mattered It settled Anthropic’s position around coding and long-running agent tasks, the ground it contested with OpenAI’s Codex and Google’s Gemini through the rest of 2025.