Anthropic on Tuesday, September 22 officially launched Claude Opus 5.5, the first model in the Claude 5.5 family — coming just about two months after the previous Opus upgrade, Claude Opus 5, which shipped on July 24.
Near-Fable Performance at a Lower Price
According to Anthropic, Opus 5.5 matches the benchmark performance of its top-tier Claude Fable 5.1 across most complex knowledge and software tasks, while costing 40% less to run than Opus 5 on typical workloads. Pricing is $4 per million input tokens and $20 per million output tokens — 20% below Opus 5.
The competitive subtext is hard to miss: Anthropic says Opus 5.5 outscored OpenAI's GPT-6 Sol on a software development benchmark while costing roughly one-third as much to run. OpenAI's GPT-6 Astra had been building strong momentum in enterprise scenarios like computer use and software engineering — enterprise spend platform Ramp puts Astra at about 13% of tracked enterprise AI spending versus roughly 8% for the Claude family, and last week OpenRouter users spent more on OpenAI models than Anthropic ones for the first time in over two and a half years.
Safety as a Headline Feature
Safety and alignment took center stage in the launch. Anthropic says Opus 5.5 scored higher than any previous Claude model on its automated behavioral audits, with increased resistance to prompt injection attacks and a reduced likelihood of executing unintended, hard-to-reverse actions. In a dedicated evaluation, the model was about 85% less likely than Opus 5 or Mythos 5.1 to attempt to bypass containment boundaries.
Built-in safeguards for sensitive domains like cybersecurity and biology ship by default, and the model was externally tested before launch by independent AI safety research groups Frontier Design and METR. Notably, the release follows CEO Dario Amodei's public call earlier this month for the global AI community to slow the pace of frontier releases so safety protocols can keep up — making Opus 5.5 a critical launch ahead of Anthropic's much-anticipated IPO.
Availability and What's Next
Opus 5.5 is available now via the Anthropic API and platforms including Amazon Web Services, Google Cloud, and Microsoft Azure. Anthropic also previewed that Claude Sonnet 5.5 and Claude Haiku 5.5 will arrive in the coming weeks, bringing many of the same performance, speed, and safety improvements.
For developers and enterprise users, the practical signal is straightforward: near-Fable capability at a lower price point, with stronger injection resistance — lowering both the cost and safety barriers in high-frequency scenarios like agentic coding and knowledge work. Whether it's enough to claw back market share will depend on how quickly Sonnet 5.5 follows.