Kimi K2

Kimi K2 is a large language model developed by Moonshot AI, a Beijing-based company backed by Alibaba, and its release was widely compared to DeepSeek's impact on the open AI ecosystem. The model is built on a Mixture-of-Experts architecture that pairs roughly one trillion total parameters with about thirty-two billion active parameters per token, a design that delivers strong capacity while keeping inference costs closer to those of a 30B-scale model. Pre-training drew on 15.5 trillion tokens and used a custom MuonClip optimizer, which Moonshot credits with maintaining stability at trillion-parameter scale.

In practical terms, K2 is aimed at agentic coding and complex reasoning workloads. On SWE-bench Verified, Moonshot reports 65.8% accuracy in a single-attempt setup, rising to 71.6% when parallel test-time sampling is combined with an internal scoring model. The original release supports a 128,000-token context window, with later K2 Thinking and K2.5 variants extending that window to 256,000 tokens. Its combination of open weights, large effective context, and strong software-engineering benchmark results makes it a natural fit for teams building autonomous coding assistants and other long-horizon reasoning tools.