Meta has released Muse Spark Open, an open-weight model designed for coding, agentic work, and multi-step reasoning. The natively multimodal system has 816 billion total parameters, with 42 billion active, and supports a 1 million-token context window.
Muse Spark Open -- weights releasing today -- runs great on new Mac Studios thanks to work with @johnternus and Apple. pic.twitter.com/U2wJNrKBOg
— Mark Zuckerberg (@finkd) October 15, 2026
The model can run locally across two Apple M5 Ultra Mac Studios using MLX. Each machine can provide up to 512 GB of unified memory, allowing the pair to hold the full model.
It’s a big day for the Mac! Mac mini and Mac Studio provide a huge leap in performance, especially for AI. pic.twitter.com/50w4DO1onL
— John Ternus (@johnternus) September 22, 2026
Meta says it tested on-device workflows that included shipping iOS changes, completing builds, and controlling DaVinci Resolve to review and crop footage.
Today, we’re releasing the weights for Muse Spark Open, giving developers more control over how they run, customize and deploy the model. (1/5) pic.twitter.com/km2V3Nl8JO
— Meta for Developers (@MetaforDevs) October 15, 2026
Muse Spark Open is also available through APIs from Baseten, Fireworks AI, Groq, Modal, Nebius, OpenRouter, and Together AI. You can download its weights from Amazon SageMaker AI, Google Cloud Model Garden, Hugging Face, and Microsoft Foundry Models. Meta is releasing them under the Muse Model License, which permits free use for many developers but includes limited commercial terms.
Sources and related context
- Muse Spark Open model card and license: Supports: Meta's model card confirms the parameter counts, 1M-token context window and MLX deployment, and includes the model's commercial license conditions.
