Meta Muse Spark Open: 816B Open-Weight Model Runs on Mac Studio
Muse Spark Open is Meta’s new open-weight AI model, released October 15, 2026. It has 816B total parameters (42B active) and a 1M-token context window, and Meta calls it the most capable US open-weight model so far.
The model is a natively multimodal mixture-of-experts (MoE) system. It takes text, images, audio and video as input and returns text. Meta built it for coding, long-horizon agentic tasks and multi-step reasoning. According to Hugging Face, each MoE layer has 256 experts, 8 of which are chosen per token.
The headline is the Apple partnership. Working with Apple, Meta optimized the NVFP4 checkpoint to run locally on two 512 GB M5 Ultra Mac Studios, or four 256 GB units, using Apple’s MLX framework over Thunderbolt 5 RDMA. Axios notes that the model is free to download under a license that allows commercial use. Because it runs locally, Meta never receives users’ prompts.
You can download the weights from Hugging Face. Hosted access is available through providers including Together AI, Fireworks, Groq and OpenRouter.
FAQ
What hardware does Muse Spark Open need to run locally?
Two M5 Ultra Mac Studios with 512 GB each (or four with 256 GB) via MLX, or 4–8 NVIDIA Blackwell GPUs.
Is Muse Spark Open free for commercial use?
Yes. The weights are downloadable under a license that permits commercial use.