Moonshot AI released Kimi K3.1 Pro on Friday, a post-trained version of Kimi K3 with a 1 million-token context window, live now on Kimi.ai, the Kimi apps, Kimi Work, Kimi Code and the Kimi API. Moonshot calls it its most capable 3T-class open-weight model to date: 2.8 trillion total parameters with 104 billion active per token, text and image input, priced at $2 per million input tokens and $10 per million output — a third below K3 — with a Highspeed variant running two to three times faster at double the price.

Artificial Analysis scores it 55 on its Intelligence Index, fourth overall and an 11-point jump over K3, behind only Claude Opus 5.5, Claude Sonnet 5.5 and Muse Wonder Full. In Moonshot's own table it scores 65.7% on Terminal-Bench 4.0 against 66.4% for Opus 5.5, though almost every coding score was run inside Anthropic's Claude Code harness and the figures are not independently checked.

The full weights are promised by November 4; if they land as promised, K3.1 Pro would become the highest-scoring open-weights model on the Index. Moonshot also says it deliberately removed hacking-related data from training ahead of the open-weight release.

Reuters filled in the cyber curb on October 24: Moonshot said it removed cyber-related data not just from the training corpus but from the reinforcement-learning environments too, while keeping general coding skills. 'We aim not to release open weights that would extend the absolute frontier of cyber capability,' the company said; on its internal vulnerability-research test the final model scored 81.0%, against 90.5% for a checkpoint without the change (vendor-reported). The restraint lands a week after China proposed export controls that would ban exports of AI-driven malware-generation technology.