From the source
Moonshot AI released Kimi K3.1 Pro, a 2.8T-parameter open-weight model with 104B active parameters and a 1M-token context window, positioned against the strongest proprietary models on coding, agentic and knowledge benchmarks.
- The model is a post-trained version of Kimi K3 with much larger post-training compute, and Moonshot ran joint reinforcement learning across hundreds of downstream domains.
- It is live on Kimi.ai, Kimi Work, Kimi Code and the Kimi API, with API IDs kimi-k3.1-pro and kimi-k3.1-pro-highspeed on an
OpenAI-compatible endpoint.
- Pricing is $2.00 input and $10.00 output per million tokens, with cache hits at $0.20; Highspeed costs $4.00 input and $20.00 output, while K3 was priced at $3.00 and $15.00.
- Moonshot reports Terminal-Bench 4.0 at 65.7%, just behind Claude Opus 5.5 at 66.4%, and a leading SWE-Marathon score of 51.7, but trails on Terminal-Bench Science 0.1 at 38.1 versus 68.1 for GPT-6 Astra.
- Weights are not public yet, with open weights expected in November 2026, and Moonshot removed cyber-related data from mid-training and RL for the open-weight release.