“It’s the new leading model, and early testers saw large jumps in performance on their most complex work,” Anthropic said in a Tuesday (Sept. 22) announcement.
Claude Opus 5.5 is now available on the Claude Platform as well as Amazon Web Services, Google Cloud and Microsoft Azure, according to the announcement.
Opus 5.5 is also highly ranked in safety, Anthropic said. The model was tested before release by external evaluators, performed stronger than other models on Anthropic’s automated behavioral audit and is equipped with the safeguards Anthropic developed for its most capable models, per the announcement.
Anthropic also highlighted Opus 5.5’s communication capabilities, saying the model’s writing is more natural, clearer and easier to follow than that of Opus 5.
Summarizing the model’s capabilities, Anthropic said: “On our benchmarks, Claude Opus 5.5 leads in agentic coding, computer use and knowledge work. That said, at these levels of capability we’ve found that benchmark margins have become a less reliable guide to real-world differences. In our own use, the gap between Opus 5.5 and Claude Fable 5.1 is narrower than these scores suggest.”
It was reported Monday (Sept. 21) that a growing number of software companies are turning to open-weight AI models, including Chinese ones, due to the cost of proprietary models from U.S. AI developers.
Anthropic’s lower-cost model arrived at a time when the company is reportedly preparing to launch its initial public offering. It was reported Friday (Sept. 18) that the company is planning to launch its IPO in November, later than the October debut many investors had expected, and that the later date may have been chosen to allow Anthropic to share its third-quarter financials, which are expected to show strong results.
It was also reported Friday that Anthropic was considering the launch of a new AI model before the company goes public in order to offset the momentum rival AI startup OpenAI has enjoyed since debuting its GPT-Astra.
