Claude Opus 5.5 is available today! Opus is the workhorse for most people, so we
By Rahul Patil · September 23, 2026 · Curated by George's Blog
Claude Opus 5.5 is available today! Opus is the workhorse for most people, so we obsessed over customer feedback in three areas:
(a) Cost per successful outcome. Opus 5.5 performs at the level of Claude Fable 5.1 on most work, and at default settings it costs 40% less to run than Opus 5 on typical workloads. That comes from lower pricing ($4/$20 per million tokens, cache reads down 60%) and from the model simply using fewer tokens per task.
(b) Tone. Opus 5.5 writes more clearly and puts the most important information up front, which means its work is easier to review and it's a better partner over long sessions.
(c) Alignment. On our automated behavioral audit, the most comprehensive alignment test we run, it's the strongest model we've tested to date. The model itself also has stronger defenses. On prompt injection attacks, it matches or beats Opus 5 in every setting we tested, including coding, tool use, computer use, and web browsing.
And yes, Sonnet 5.5 and Haiku 5.5 follow in the coming weeks, with many of the same gains!
Thank you for the feedback. Keep it coming. Happy building. https://lnkd.in/gDw9Hp3X