# Meta releases Muse Spark Open, an 816B open-weight model

> Meta released Muse Spark Open, an 816B-parameter open-weight multimodal model aimed at coding and agentic tasks.

*The multimodal model targets coding and agentic work, and Meta calls it the most capable US open-weight model to date.*

By Bez · FeaturedDaily
Canonical: https://featureddaily.com/news/meta-releases-muse-spark-open-an-816b-open-weight-model

**What happened:** Meta has released Muse Spark Open, a natively multimodal open-weight model. [Meta AI Research](https://research.meta.ai/blog/muse-spark-open) calls it "the most capable US open-weight model to date."

**The numbers:** It has 816B total parameters, with 42B active in a mixture-of-experts design. The context window is 1M tokens.

**The focus:** Meta is aiming at coding and agentic work: long-horizon tasks, complex software engineering and multi-step reasoning.

**Run it locally:** Two Apple M5 Ultra Mac Studios can run it via MLX. Each offers up to 512 GB of unified memory and 1.2 TB/s of bandwidth. Together they act like one machine with about 1 TB of memory.

**Where to get it:** Weights are on Hugging Face, Amazon SageMaker AI, Google Cloud Model Garden and Microsoft Foundry Models. Hosted APIs come from Baseten, Fireworks AI, Groq, Modal, Nebius, OpenRouter and Together AI.

**The details:** Supported engines include SGLang, vLLM, TensorRT-LLM, Transformers, MLX, llama.cpp and Unsloth. Helion kernels in SGLang deliver 1.03–3.95x kernel speedups on Nvidia and AMD GPUs.

**The licence:** Weights ship under the Muse Model License, which has limited commercial terms. Many developers can use the model free of charge.

**The catch:** The blog's benchmark section gave no figures in the extracted text. The performance claims await independent testing.

**Why it matters:** Meta says the model received extra safety post-training and met the release thresholds in its Meta Superintelligence Scaling Framework.

**What's next:** Meta says the full evaluation report will be "available soon."

## Key takeaways

- 816B parameters, 42B active, 1M-token context
- Runs locally on two Apple M5 Ultra Mac Studios
- Benchmark claims still await independent testing

## Sources

- [Muse Spark Open](https://research.meta.ai/blog/muse-spark-open) — Meta AI Research, 2026-10-15