Moonshot AI said in an official X post1 that Kimi K3.1 Pro, which it described as its most capable 3T-class open-weight model, would have open weights by Nov. 4, 2026.
The announcement matters because Moonshot is positioning the model as a self-hostable alternative to API-only access, but the material in hand establishes only what the company announced, not independent performance or a verified weights release.
Moonshot's post said Kimi K3.1 Pro has a 1 million-token context window, 2.8 trillion total parameters, and 104 billion active parameters in a mixture-of-experts design, and that it is multimodal, according to the official X post1. The company also said K3.1 Pro and a K3.1 Pro Highspeed variant that it described as 2-3x faster were live on Kimi.ai, Kimi Work, Kimi Code and the Kimi API, according to the same post1.
Moonshot further claimed the model supports full-project coding for Unreal, Unity and Godot, performs well in Blender and CAD workflows, and is "more reliable at finance work," with hallucination "down by 65%," according to the official X post1. The post includes no independent test results.
A separate post from @hiarun02 on X2 said Moonshot AI "has released Kimi K3.1 Pro with open weights," repeating the 2.8 trillion-parameter and 1 million-token figures. That post is a third-party social post and does not independently verify availability.
For background, an alphaXiv page summarizing Moonshot's tech blog3 described K3.1 Pro as a post-trained version of Kimi K3 and repeated Moonshot's claims about coding, 3D creation, finance and agentic benchmarks. That page is not Moonshot's own site, and its benchmark summary mixes issuer claims with third-party context.
The same alphaXiv page said K3.1 Pro scored 65.7% on Terminal-Bench 4.0, compared with 58.2% for GPT-6 Astra and 66.4% for Claude Opus 5.5, and 92.7% on BenchCAD with tools, compared with 96.2% for Claude Opus 5.5 and 95.9% for GPT-6 Astra, according to alphaXiv3. But those figures are presented through a secondary page rather than an issuer-hosted technical report in the material provided here, so they should be treated as reported claims rather than independently established test results.
Another secondary report from RuntimeWire4 said Moonshot released the model weights on Nov. 4, 2026, completing the commitment in the October announcement. RuntimeWire said that release was linked from an X post to a Hugging Face repository, but neither the referenced issuer post nor the repository is included here, so that step could not be directly confirmed from the available documents.
On the record available here, the firm basis is Moonshot's own announcement of Kimi K3.1 Pro's specifications, product availability across its services, and its stated plan to provide open weights by Nov. 4, 2026, as set out in the company's official X post1.