Alexandr Wang Says Muse Spark Is the Most Capable US Open-Weight Model to Date

What happened

1/ Muse Spark open is the most capable US open-weight model to date. 816B total params, 42B active. 1M-token context. Natively multimodal. Built for coding and agentic work like long-horizon tasks, hard software engineering, and multi-step reasoning. America! 🇺🇲

Reported by 10 sources

The story so far

Meta released downloadable weights for Muse Spark Open, a multimodal model built for coding and agentic work, with local Mac and cloud deployment options. Artificial Analysis ranks it first among US open-weight models on its Intelligence Index, with a score of 39 at the xhigh setting. The model has approximately 816 billion parameters, 42 billion active per token, and up to one million tokens of context. It accepts text, images, audio and video and generates text. Meta says it can run on two Apple M5 Ultra Mac Studios using MLX; Baoyu reports that the configuration uses 512GB of unified memory per machine. vLLM says its support is verified on NVIDIA and AMD GPUs and TPUs. Ollama Cloud offers access through Pro, Max, Pay-as-you-go and Teams plans. Amazon SageMaker JumpStart offers BF16 and NVFP4 variants in US East (N. Virginia) and US East (Ohio) at launch, charging for endpoints whenever they are running, including while idle. The Decoder reports that free use requires the label “Built with Muse Spark Open.” Baoyu reports that attribution and usage restrictions apply, and businesses selling API access to the model or modified versions must notify Meta and sign a separate agreement if their combined revenue with affiliates exceeded $20 million over the preceding 12 months.

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