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 The release paired coding-focused models with a generally available developer tool for software work, including tasks requiring extended reasoning.
Corrections
- 2026-09-13: Replaced the Wikipedia overview with Axios reporting published on 2025-05-22 and narrowed the consequence to the capabilities and developer tool documented at launch, without claiming a settled market position through the rest of the year.