Anthropic launches Claude Opus 5.5: top benchmark performance at 40% less than Opus 5
minchoi · x · 2026-09-23
- Anthropic released Claude Opus 5.5, the first model in the Claude 5.5 family, matching Fable 5.1 on most work at 40% less cost than Opus 5.
- Live today on Claude, API, AWS, Google Cloud, and Azure; Sonnet 5.5 and Haiku 5.5 arrive in the coming weeks.
- Tested pre-release by external evaluators including Frontier Design and METR; strongest model to date on Anthropic's automated behavioral audit, with better resistance to irreversible actions and prompt injection.
- Highlights: one tester completed a 680,000-line code migration in under a day; it cut web app load times in 39 of 40 tries; it built the best single-prompt game among Claude models.
Related event: Anthropic Launches Claude Opus 5.5: Smarter, Faster and 40% Cheaper(55 posts)→
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