Claude Sonnet 4 spotted on OpenRouter
Claude Sonnet 4 from Anthropic was first recorded on 21 Sep 2026. Its release date is not established. 6 evidence links.
Alex's take
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Evidence links 6
- OpenRouterfirst · openrouter.ai
- OpenCode · discoveryevidence linkopencode.ai
- models.dev · catalogueevidence linkmodels.dev
- models.dev · catalogueevidence linkmodels.dev
- Anthropic · API pricingevidence linkplatform.claude.com
- Arena · leaderboardsevidence linkanthropic.com
Related signals
AnthropicSightingClaude Haiku 5.5 (Max, Default Fallback) enters at 43.4 on the Intelligence Index
Confirmed20 evidence links