# Meta — Introducing Muse Spark Open, The Most Capable US Open‑Weight Model to Date

- Company: Meta (meta.com)
- Announced: 2026-10-15
- Category: open-weight-release
- Coverage: not counted
- Announcement: yes
- Group: models
- Source: https://research.meta.ai/blog/muse-spark-open
- Record: https://forck.live/items/22973-introducing-muse-spark-open-the-most-capable-us-open-weight-model-to-date
- Subject: Muse
- Open weights: yes
- Models affected: Muse Spark Open
- License: Muse Model License with limited commercial terms
- Context window: 1M-token context window

Meta released Muse Spark Open, an open-weight multimodal model with 816B total parameters (42B active) and a 1M-token context window, optimized for coding and agentic tasks. The model weights are available for download on platforms including Hugging Face, Amazon SageMaker AI, and Google Cloud Model Garden, and it can run on two Apple M5 Ultra Mac Studios using the MLX framework. Meta released the weights under the Muse Model License with limited commercial terms.

## Evidence

Verbatim from https://research.meta.ai/blog/muse-spark-open:

> Muse Spark Open is a natively multimodal model with 816B total parameters (42B active) and a 1M-token context window. Built for coding and agentic work, it excels at long-horizon tasks, complex software engineering, and multi-step reasoning.

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Record: https://forck.live/items/22973-introducing-muse-spark-open-the-most-capable-us-open-weight-model-to-date
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