Moonshot's Kimi account announces Kimi K3.1 Pro, which it calls its most capable 3T class open weight model, live now on its apps and API with weights promised by November 4
Deep dive
The Kimi account says Kimi K3.1 Pro is its most capable 3T class open weight model, with a 1 million token context window, 2.8 trillion total and 104 billion active parameters in a mixture of experts design, and multimodal input. It says K3.1 Pro and a K3.1 Pro Highspeed version, which it describes as 2 to 3 times faster, are live on Kimi.ai, Kimi Work, Kimi Code and the Kimi API, and that open weights arrive by November 4, 2026. The tech blog adds that access for Kimi Enterprise organizations is off by default at launch.
The tech blog describes K3.1 Pro as a post trained version of Kimi K3, and the K3 technical report gives the same parameter and context figures.
Kimi's own figures put K3.1 Pro at 65.7% on Terminal Bench 4.0, ahead of GPT 6 Astra at 58.2% and just behind Claude Opus 5.5 at 66.4%, and the attached chart shows it first on six of fourteen benchmarks. On Kimi's internal hallucination stress test, the blog says the claim level rate fell from 23.4% for K3 to 8.3%, and says that is not an everyday error rate.
Artificial Analysis, an independent benchmarking firm, posted at 1:44 PM Eastern that K3.1 Pro ranks 4th on its Intelligence Index with 55, up 11 points from K3, behind Claude Opus 5.5 at 58 and Claude Sonnet 5.5 and Muse Wonder Full at 56. In its testing K3.1 Pro scored 67% on Terminal Bench 4.0, which it calls the highest of any model, and its hallucination rate on AA Omniscience fell from 53% to 44%. It lists API prices of $2 input and $10 output per million tokens, 33% below K3, and notes the weights are not yet published.
On security, Kimi says it removed cyber related data from training for the open release, and that on its in house exploit benchmark a checkpoint without that step solved 90.5% of tasks against 81.0% for the final model. Those figures have not been independently checked.