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Moonshot AI Kimi K3 Open-Source Multimodal Model

Moonshot AI, a Chinese startup, has launched Kimi K3, an open-source multimodal AI model with 2.8 trillion parameters. It claims to outperform some leading proprietary models in specific benchmarks and supports a 1-million-token context window.

AIOpen-SourceMultimodalMoonshot AIKimi K3Large Language ModelChina

Resource Overview

Moonshot AI, a prominent Chinese start-up, has introduced Kimi K3, which it asserts is the world's largest open-source artificial intelligence model [1]. This release signifies a notable advancement in the open-source AI landscape, particularly from a Chinese developer, aiming to narrow the gap with leading US rivals [1].

Key Content

Kimi K3 boasts an impressive architecture with 2.8 trillion parameters, making it substantially larger than previous open models from Chinese competitors [1]. This model is engineered for advanced tasks such as long-horizon coding, complex knowledge work, and sophisticated reasoning [1]. A key feature is its native handling of various data types, including text, images, and video, alongside support for an extensive 1-million-token context window [1].

To facilitate practical deployment, Kimi K3 utilizes MXFP4 weight quantization, which significantly reduces its storage footprint to approximately 1.4 TB. This optimization is crucial for enabling multi-node self-hosting [1]. Moonshot AI claims that Kimi K3 has achieved "open frontier intelligence" and has demonstrated superior performance over OpenAI's GPT-5.5 and Anthropic's Claude Opus 4.8 in specific evaluations, including Program Bench and SWE Marathon [1].

How to Use

The full open weights for the Kimi K3 model are anticipated to be released on July 27, 2026 [1]. For developers and businesses, API pricing for Kimi K3 is set at approximately $3 per million input tokens and $15 per million output tokens, which is noted as being more cost-effective than comparable U.S. frontier models [1].

Notes and Caveats

While Kimi K3 has shown strong performance in certain benchmarks, Moonshot AI acknowledges that its overall capabilities still trail the most powerful proprietary models currently available [1]. Additionally, users should note that the full open weights for the model are not yet publicly accessible, with the release planned for July 27, 2026 [1].

Sources

  • South China Morning Post, "Moonshot AI unveils world's largest open-source AI model as China narrows gap with US rivals", published on 2026-07-17 [1]
  • AI Weekly Pulse, "AI News This Week: AI model releases July 2026 | AI Weekly Pulse #4", published on 2026-07-18 [2]