Muse Spark Open, the Most Capable US Open‑Weight Model to Date
Meta released Muse Spark Open, an 816B multimodal open-weight model with 42B active parameters and a 1M-token context.
Meta released weights for Muse Spark Open, a natively multimodal mixture-of-experts model with 816 billion total parameters, 42 billion active, and a one-million-token context window, built for coding and agentic work. Meta calls it the most capable US open-weight model and says it is the first in its class to run locally on two Apple M5 Ultra Mac Studios via MLX, using up to 512 GB of unified memory per machine. Weights are on Hugging Face, Amazon SageMaker, Google Cloud Model Garden, and Microsoft Foundry, with APIs at Baseten, Fireworks, Groq, Modal, Nebius, OpenRouter, and Together AI. The Muse Model License has limited commercial terms, and Meta says safety post-training met its Superintelligence Scaling Framework release thresholds.