The Sequence AI of the Week #753: Inside Kimi K2 Thinking: The Architecture of Long-Horizon Reasoning
Without a doubt, one of the most impressive open source models ever released.
Kimi K2 Thinking is Moonshot AI’s bid to redefine what it means for a large language model to “think.” Rather than being a chat model that produces a single-shot answer, K2 Thinking behaves like an autonomous solver—capable of reasoning, planning, and acting over long horizons without losing coherence. It is built upon the Kimi K2 backbone, a trillion-parameter mixture-of-experts (MoE) Transformer with roughly 32 billion active parameters per token. Around this backbone, Moonshot has developed a multi-layered training process that combines large-scale data efficiency, reinforcement learning for tool use, and native support for interleaved reasoning.