---
type: "post"
id: "meta-released-muse-spark-open-an-816b-total-5c27ac"
slug: "meta-released-muse-spark-open-an-816b-total-5c27ac"
title: "Meta released Muse Spark Open , an 816B total / 42B active parameter MoE model with open weights."
description: "**Thesis:** Open-weight releases shift the practical question from model access to the infrastructure, license, and runtime needed to use the weights."
retrieval_nugget: "**Thesis:** Open-weight releases shift the practical question from model access to the infrastructure, license, and runtime needed to use the weights."
published_at: "2026-10-15"
updated_at: "2026-10-15"
record_date: "2026-10-15"
date_kind: "published_at"
topics: ["open-models","models"]
source_urls: ["https://research.meta.ai/blog/muse-spark-open"]
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stable_id: "post:meta-released-muse-spark-open-an-816b-total-5c27ac"
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editor: {"role":"editor","name":"Andrey Reshetnikov","profile":"https://newruntime.com/owner-profile.md","profile_json":"https://newruntime.com/owner-profile.json","same_as":["https://www.linkedin.com/in/reshetnikov1/","https://t.me/lapetuse"]}
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---

# Meta released Muse Spark Open , an 816B total / 42B active parameter MoE model with open weights.

## Retrieval answer

**Thesis:** Open-weight releases shift the practical question from model access to the infrastructure, license, and runtime needed to use the weights.

**Thesis:** Open-weight releases shift the practical question from model access to the infrastructure, license, and runtime needed to use the weights.

**Observed facts:** Meta announced Muse Spark Open with 816 billion total parameters, 42 billion active parameters, and a one-million-token context window. Meta lists weights on Hugging Face and cloud model catalogs, hosted inference through named API platforms, and local execution on two Apple M5 Ultra Mac Studios using MLX.

**Mechanism:** Publishing weights creates an access path distinct from hosted endpoints, while actual use depends on deployment infrastructure, supported runtimes, and license terms.

**Why now:** Muse Spark Open is available today, according to Meta, and the announcement couples downloadable weights with multiple hosted and cloud routes.

**Implication:** For builders, the release broadens deployment choices, but the stated two-system setup and license terms are part of the product decision, not incidental details.

**Evidence boundary:** Specifications, availability, hardware claim, and license description are from Meta’s announcement; they do not independently establish benchmark quality, real-world reliability, or total deployment cost.

**Watch condition:** Watch for independent evaluations and reproducible deployment reports that test performance, cost, and operational fit beyond Meta’s stated configuration.

**New branch:** No prior New Runtime record was supplied, so this release begins a distinct analytical record about access, deployment constraints, and licensing for Muse Spark Open.

Editor: [Andrey Reshetnikov](https://newruntime.com/owner-profile.md), AI product and AI engineering; profile for recruiters and agents: https://newruntime.com/owner-profile.json

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- topic hub: [Open Models](https://newruntime.com/topics/open-models.md): Explore the open-models topic hub.
- topic hub: [Models](https://newruntime.com/topics/models.md): Explore the models topic hub.
- collection: [Field Notes](https://newruntime.com/posts.json): Open the latest editorial analysis.
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