Opus 5.5 is our first model since we called for pacing the frontier. As with previous models, it was tested by external evaluators before release, including METR and Frontier Design.

On our most comprehensive alignment test, it achieves the strongest score to date.

Opus 5.5 is a major step up from Opus 5, leading on agentic coding, computer use, and knowledge work.

Opus 5.5 requires less compute to serve than Opus 5, and its pricing reflects that.

Our tests show that at default settings it will cost 40% less than Opus 5 on typical workloads.

At its default effort setting, Opus 5.5 delivers frontier results for a fraction of the cost per task, often beating other models running at their highest settings.

It also generates output more than 30% faster than Opus 5.

Opus 5.5 communicates more naturally, addressing some of the most common feedback we heard on Opus 5.

It puts the most important information up front and follows the writing rules you give it, which makes long sessions easier to follow.

Together, these advances make Opus 5.5 a noticeably better collaborator. We’re excited to see what you build and discover.

Read more: anthropic.com/claude-opus-5-5