Changes from previous version
Launched alongside Claude Opus 4; same $3/$15 API pricing as prior Sonnet tiers with major coding and agent gains.
Release Summary
Claude Sonnet 4 hybrid model with instant and extended thinking modes, 72.7% SWE-bench Verified, and sharper instruction following versus Sonnet 3.7.
Timeline
May 22, 2025
Claude Sonnet 4 released
Anthropic releases Claude Sonnet 4 and Opus 4, with Claude Code reaching general availability.