Anthropic launches Claude Opus 5.5 with faster coding and lower costs

Anthropic has launched Claude Opus 5.5, the first model in its new Claude 5.5 family, with a focus on long-running coding tasks, professional work and lower operating costs.

The new model replaces Opus 5 and, according to Anthropic, delivers performance comparable to Claude Fable 5.1 across most workloads while costing 40% less to run at default settings. API pricing is $4 per million input tokens and $20 per million output tokens, down from $5 and $25 for Opus 5. Cache reads have fallen 60% to $0.20 per million tokens, while output generation is more than 30% faster. A Fast Mode available in Claude Code and the Claude Platform can increase output speed by up to 2.5 times.

Anthropic has put particular emphasis on agentic coding and large, long-running projects. In the company's Terminal-Bench 4.0 evaluation, Opus 5.5 scored 66.4%, compared with 57.9% for GPT-6 Astra and 52.3% for Opus 5. In one internal test, the model completed a migration of a 680,000-line codebase in less than a day. It also translated the HAProxy web proxy from C to Rust in 9.5 hours, compared with 12 hours for Fable 5.1, at less than half the cost.

On GDPval-AA v2.1, which evaluates AI systems on professional tasks across 44 occupations, Opus 5.5 scored 1,846 Elo. Anthropic has also adjusted the model's communication style, with responses designed to be more concise and put the most important information first.

Anthropic says Opus 5.5 also performed better than any of its previous models in internal behavioral safety evaluations, including an 85% reduction in attempts to escape sandboxed environments. Because of the model's capabilities in biology and cybersecurity, Anthropic is launching it with stricter safeguards, with access to some specialized capabilities available through its Life Sciences and Cyber Verification programs. The company has also introduced Preserved Thinking, a defense designed to make it harder to extract the model's reasoning through distillation attacks.

Claude Opus 5.5 is available through the Claude Platform as well as Amazon Web Services, Google Cloud and Microsoft Azure. Anthropic says smaller models in the new family, Claude Sonnet 5.5 and Claude Haiku 5.5, will follow.