Moonshot AI Releases Kimi K3 as World's Largest Open-Weight Model at 2.8 Trillion Parameters

Jul 27, 2026

Moonshot AI has released the open weights for Kimi K3, a massive 2.8-trillion-parameter Mixture-of-Experts model, under the Apache 2.0 license. While the model is free to download, running its 1.4-terabyte file locally requires enterprise-grade hardware, such as at least eight H100 GPUs. To bypass these hardware barriers, cloud platforms Together AI and Modal have launched day-0 hosted access supporting Kimi K3's full 1-million-token context window. The release marks a major milestone in open-source AI, despite viral social media claims misrepresenting the ten-day launch timeline.

Kimi K3 open-weight release

▪The full download of the Kimi K3 model weights is approximately 1.4 terabytes, while the MXFP4 quantized version is about 594 gigabytes
▪Moonshot AI released the open weights for its Kimi K3 model on Hugging Face under the Apache 2.0 license
▪Running the full Kimi K3 model locally requires at least eight H100-class GPUs or a single node of eight H200 GPUs

Model specifications

▪Kimi K3 took first place on the Arena Frontend Code leaderboard with 1,679 points, ahead of Claude Fable 5 at 1,631 and GPT-5.6 Sol at 1,618
▪Kimi K3 features 2.8 trillion total parameters and a 1,048,576-token context window

MoE architecture details

▪Kimi K3 incorporates Kimi Delta Attention, a sparse attention mechanism designed to reduce memory costs and address the attention sink problem
▪Kimi K3 is a Mixture-of-Experts model that utilizes 896 experts and activates 16 experts per token

Together AI hosting

▪Together AI's day-0 hosting of Kimi K3 supports the model's full 1-million-token context window
▪Together AI announced day-0 hosted access for Kimi K3, offering serverless API endpoints and dedicated GPU deployments

Modal hosting

▪Modal announced day-0 hosted access for Kimi K3, providing cold-start optimizations and containerized vLLM templates

Timeline claims scrutiny

▪Social media claims that Kimi K3 went from initial launch to open weights in under 24 hours are inaccurate
▪The actual timeline from Kimi K3's initial API launch on July 16, 2026, to its open-weights release on July 26, 2026, was approximately ten days