MetaAnalysisMeta releases 816B open-weight Muse Spark Open multimodal model
What happened.Meta released open weights for Muse Spark Open, an 816-billion-parameter multimodal mixture-of-experts model built for autonomous software engineering.
Why it matters.Proprietary frontier models retain high per-token API pricing. Open weights of this scale let engineering organizations self-host private coding agents without sending proprietary corporate code to external vendors.
The technical specifications:
- Active routing: Routes tokens across 256 experts to activate 42 billion parameters per forward pass while keeping compute demands manageable.
- Long context: Houses a 1-million-token context window that reads complete software repositories and associated documentation in a single prompt.
- Model weights: Distributes checkpoints in BF16 and NVFP4 formats on Hugging Face under the Muse Model License for local and cloud deployment.