Kimi K3.1 Pro: an open-weight model within 3 points of the frontier
Kimi's K3.1 Pro model is listed as available in the company's mobile app, Shanghai, China, October 24, 2026. (Photo: VCG)
Moonshot AI released Kimi K3.1 Pro on Friday, and it debuted fourth on the Artificial Analysis Intelligence Index with a score of 55, trailing only Anthropic's Claude Opus 5.5 and Sonnet 5.5 and Muse Wonder Full.
Once the Chinese startup publishes the full weights, expected by November 4, K3.1 Pro will become the highest-scoring open-weight model ever released, narrowing the gap between the leading open-weight and proprietary systems from 12 points to 3, according to Artificial Analysis.
The model is a post-trained version of Kimi K3, the 2.8-trillion-parameter system Moonshot fully open-weighted in July, which was then the largest open-weight model in existence. K3.1 Pro retains the 3-trillion-parameter class and a 1-million-token context window.
The new model's biggest gain is on Terminal-Bench 4.0, which tests coding agents on real terminal tasks: K3.1 Pro scores 65.7%, ahead of OpenAI's GPT-6 Astra at 58.2% and close to Claude Opus 5.5 at 66.4%. Pricing is $2 per million input tokens and $10 per million output, half the rate card of Claude Opus 5.5.
The release drew roughly 850 points on Hacker News, a score that reflects both upvotes and comment activity, with nearly 500 comments by Friday evening. The most discussed trait was temperament. "Kimi is so much more blunt and argumentative than USA models," one highly visible comment read. "It's so funny, it will say things like, 'We've already been over this 3 times and you refuse to accept my advice, asking the same question another way won't change the answer.'"
The unresolved question is whether K3.1 Pro's benchmark proximity to Claude Opus 5.5 translates into real-world equivalence. OrcaRouter notes two caveats: the Terminal-Bench scores were produced at different reasoning settings, and the two-time price advantage is per token, not per finished task. Artificial Analysis puts K3.1 Pro's cost per Intelligence Index task at $1.98, roughly equal to K3's $2.00, because it generates 55 thousand output tokens per task – 14% more than K3.
China is rising in open-weight AI. Hugging Face's 2026 report found that open models developed in China accounted for 41% of the platform's downloads, ahead of the US at roughly 35-36.5%. Science and Technology Daily wrote that Kimi K3 "has sent shockwaves through the global tech community," and Axios bluntly noted that "America's commanding lead in advanced AI is gone."
Moonshot, founded in 2023, went from a long-context chatbot to a $50 billion valuation in under four years.