Moonshot AI has released Kimi K3, a 2.8 trillion parameter model that the Beijing-based startup calls the world’s largest open-weight AI system. The announcement comes sooner than many Western analysts expected and comes as Chinese developers close in on their American counterparts.
Kim K3 features a 1 million token context window that can hold much more information in a single prompt than previous Kim releases. According to Moonshot, the model targets advanced reasoning, long-term coding, and knowledge work, and is positioned as the first model to approach the 3 trillion parameter mark.
The company is making K3 available through its own efforts and API, but the full open weight file (the part where developers can directly download and modify the model) will not be made public until July 27th.
The company says that in GPU kernel optimization, a measure of hardware efficiency, K3 “outperformed” Anthropic’s Fable 5, outperformed Anthropic’s Opus 4.8, and outperformed OpenAI’s GPT-5.6 Sol and GPT-5.5.
Independent evaluators have given mixed but impressive feedback, with Arena.ai ranking K3 first in terms of creating web interfaces, Vals AI ranking K3 second to Fable 5, and Artificial Analysis finding K3’s performance on complex multi-step tasks to be similar to GPT-5.5 and Opus 4.8.
These numbers are primarily taken from benchmarks conducted by Moonshot itself.
The announcement came as a bit of a shock to domestic competitors, with Zhipu and MiniMax’s stock prices reportedly plummeting on the Hong Kong exchange on the same day. And that trend has continued since Zai’s GLM-5.2 recently closed in on the top of the U.S. closed-source models, defying expectations that Chinese labs are at least six months behind their development. Before K3’s announcement, Meituan’s LongCat-2.0 and DeepSeek’s V4-Pro each led China with 1.6 trillion parameters.
Moonshot, backed by Alibaba and Tencent, reportedly raised $2 billion at a $30 billion valuation before listing in Hong Kong. The plan includes developing a unique 2.7 trillion parameter model by 2026.
