Anthropic launches Claude Opus 5.5

Anthropic introduced Claude Opus 5.5 on September 22, 2026, as the first model in its Claude 5.5 family. It claims Fable 5.1-level performance for most tasks and 40% lower running costs than Opus 5. Separately, a user who said they ran fresh Next.js evaluations reported 97% for Opus 5.5, GPT 6 Sol and Fable 5.1, versus 94% for Grok 4.7. They also described Grok as “2x-7x cheaper.”