Moonshot AI releases Kimi K3 open weights — largest open-weight model in history

What happened

Moonshot AI released full open weights for Kimi K3 on July 27, 2026 — a 2.8-trillion-parameter sparse Mixture-of-Experts model that is natively multimodal and supports a 1M-token context window.

Context and impact

Kimi K3 is technically the largest open-weight model release in AI history, reigniting the US-China AI rivalry debate. American labs and investors are publicly reassessing how wide the closed-frontier lead really is. Full weights (~1.4 TB in MXFP4 quantization) are freely downloadable, enabling community inference.

Details

• 2.8 trillion parameters, sparse MoE architecture
• Native text, image, and video support
• 1 million token context window
• Full weights ~1.4 TB in MXFP4 quantization
• Live via Kimi API and apps since late July 2026
• Sparked reassessment of the actual US-China AI capability gap