Meta releases Muse Spark Open weights
Meta released the weights of Muse Spark Open — a natively multimodal model for coding and agents with 816 billion total and 42 billion active parameters and a context of 1 million tokens, on Hugging Face under the Muse Model License
Why it matters
Meta claims it is the most capable US open-weights model to date. It adds safety post-training for standalone use on top of the same base model as Muse Spark 1.3, and ships with SGLang and vLLM optimizations and Helion kernels (1.03–3.95 times faster on GB300). Muse Spark, which began as a private preview in April, reached open weights within half a year
Source — Primary sources first; secondary reports are labelled “Press”
Officialpytorch.orghttps://pytorch.org/blog/muse-spark-open/Added in Week 42, 2026 · See that week