Moonshot releases Kimi K3 open weights, the largest ever

Chinese AI lab Moonshot AI released the full open weights of its Kimi K3 model on July 27, making the roughly 2.8-trillion-parameter mixture-of-experts system the largest open-weight model ever published, under a modified MIT license on Hugging Face. K3, which launched via API and kimi.com on July 16 with a 1-million-token context window and Moonshot's Kimi Delta Attention, trails Anthropic's Claude Fable 5 and OpenAI's GPT-5.6 Sol on overall benchmarks but leads other tested open models, and the open release lets developers self-host to keep data off Moonshot's servers. The drop lands days after Nvidia, Microsoft and Meta led an open letter warning US policymakers against premature restrictions on open-weight AI.