Muse Spark Open
Muse Spark Open is an open-weight mixture-of-experts model from Meta, released on October 15, 2026, with 816B total and 42B active parameters. It takes text, image, video and audio input and returns text. Meta's own Model API does not serve it: it is self-hosted or run through hosted providers.
Released
October 15, 2026
Type
multimodal
License
open-weight
Muse Model License (limited commercial terms)
Context
1,048,576 tokens
Capabilities
Architecture
Parameters: 816B total, 42B active (mixture of experts)
Sources
Every figure on this page was checked against these pages on . A figure we could not source is left out.
- Meta AI Research: Introducing Muse Spark Open (opens in a new tab)
- Meta Model API docs: Models (opens in a new tab)
- Hugging Face: meta-models/Muse-Spark-Open-816B-A42B model card (opens in a new tab)
Spotted something out of date? Tell us.
Links
In the news: Muse Spark Open and Meta
MarkTechPost
Meta Releases Muse Spark Open: 816B Open-Weight MoE With 1M Context
Meta Superintelligence Labs has released Muse Spark Open, the open-weight version of its Muse Spark model. This new model is an 816 billion parameter Mixture-of-Experts (MoE) model that activates 42 billion parameters per token. It is designed to process text, image, video, and audio inputs, returning text outputs, and boasts a 1 million token context window. Meta claims Muse Spark Open is the most capable US open-weight model released to date. For developers, a key feature is its deployment capability, with the NVFP4 build running on two Apple M5 Ultra Mac Studios. The model's architecture includes 62 layers and a hidden dimension of 8192, with each MoE layer containing 256 experts and activating 8 per token through top-k routing. The model supports multimodal input through a separate 1.8 billion parameter Perception Encoder. Its vocabulary size is 202,048 tokens, and it was trained on data covering over 100 languages. Muse Spark Open offers adjustable reasoning depth settings, defaulting to 'xhigh'. Performance benchmarks show Muse Spark Open excelling in agentic tool use and knowledge reliability, achieving a score of 89.2 on MCP-Atlas. However, it performed mid-pack on coding tasks, scoring 76.4 on Terminal-Bench, which is behind models like Kimi K3 (85.0), GLM 5.3 (83.9), and Qwen3.8 (82.0).
The Guardian AI
Meta releases Muse Spark Open, a new ‘open-weight’ AI model
The Decoder
Muse Spark Open is Meta's answer to Qwen, GLM, and Kimi in the open-weight race
Hugging Face
Welcome Muse Spark Open: open-weight frontier multimodal mixture-of-experts model from Meta
Meta has launched Muse Spark Open, a frontier multimodal mixture-of-experts AI model. The model is now available as open-weight, enabling wider access and use. This release signifies Meta's contribution to the advancement of open-weight AI models in the frontier technology space.
The Hacker News
Bring Your Own Agent: Your Employees' Assistants Are Already Logged In
The rollout of personal AI agents is encountering significant challenges, including privacy concerns and identification issues. Amazon has blocked Meta's Muse agent for failing to identify itself as a bot during browsing, and the Instinct agent has also raised privacy alarms. Despite these ongoing issues and accumulating negative experiences, the technology sector remains captivated by the capabilities and potential of these personal AI services. The article highlights that the personal AI agent rollout is proceeding with expected difficulties.