Kimi K3.1 Pro

Moonshot AI · proprietary · kimi-k3.1-pro

Kimi K3.1 Pro is the first model in Moonshot AI's K3.1 series, a post-trained version of Kimi K3 built with substantially larger post-training compute and large-scale joint reinforcement learning across hundreds of domains. Moonshot describes it as its most capable 3T-class open-weight model, with a 1,048,576-token context window, text/image/video input, tool calling, structured output, and always-on reasoning (low, high, or max; Moonshot API default max). max_completion_tokens defaults to 131,072 and can be raised to 1,048,576. It targets long-horizon coding, 3D creation and CAD, financial research, and other agentic work. Pricing is a one-third cut from K3 ($2 / $10 vs $3 / $15 per MTok). A Highspeed variant (kimi-k3.1-pro-highspeed) offers 2-3x the speed with the same capabilities at $4 / $20 (cached input $0.20). Full weights are scheduled for release by Nov 4, 2026.