From the source
Moonshot AI introduced Kimi K3.1 Pro, the first model in its K3.1 series, alongside a faster companion variant called Kimi K3.1 Pro Highspeed.
- The company describes K3.1 Pro as its most capable 3T-class open-weight model to date, with a 1-million-token context window, and says Highspeed delivers two to three times the speed of K3.1 Pro with identical model capabilities.
- Both models are available on Kimi.ai and the Kimi mobile apps, in the Kimi Work desktop application version 3.1.0 or later, in Kimi Code, and through the Kimi API as kimi-k3.1-pro and kimi-k3.1-pro-highspeed, with Zero Data Retention available for API customers.
- Kimi Enterprise administrators can enable K3.1 Pro for their organizations, with access off by default at launch.
- K3.1 Pro is a post-trained version of Kimi K3 built with substantially larger post-training compute, and Moonshot AI reports it scored 65.7 percent on Terminal-Bench 4.0, ahead of GPT-6 Astra at 58.2 percent and narrowly behind Claude Opus 5.5 at 66.4 percent.
- On Kimi Hallu Bench Hard, the company says the model's claim-level hallucination rate fell from 23.4 percent for K3 to 8.3 percent, while noting the evaluation is crafted to probe error-prone situations and the rates do not represent overall error rates in daily use.
- For the open-weight release, Moonshot AI said it removed cyber-related data from both training stages, and reports that a checkpoint trained without those measures solves 90.5 percent of xdev-bench-hard problems at pass@3 while the final K3.1 Pro reaches 81.0 percent.