Muse Spark Open (Reasoning)

by Meta

Muse Spark Open (Reasoning) is a reasoning model from Meta, released on October 15, 2026. It has a 1M-token context window and can generate up to 1M output tokens. API pricing is $1.25 per 1M input tokens and $4.25 per 1M output tokens. It ranks #41 of 247 models by Intelligence Score with a score of 45.

Muse Spark Open is Meta Superintelligence Labs' open-weight natively multimodal Mixture-of-Experts model (816B total / 42B active parameters) with a 1,048,576-token context window. The HF model card specifies text, image, video, and audio inputs and text output. It supports configurable reasoning_effort (low/medium/high/xhigh; default xhigh) and is positioned for coding and agentic workflows. Weights are released under the Muse Model License with limited commercial terms and are available on Hugging Face as meta-models/Muse-Spark-Open-816B-A42B (BF16) and an NVFP4 sibling. Hosted inference is offered by third-party providers including Together AI, Fireworks AI, Groq, Modal, Nebius, Baseten, and OpenRouter (slug meta/muse-spark-open).

Key specs

ProviderMeta
Release date2026-10-15
Licenseopen weights
Context window1M tokens
Max output1M tokens
Input price$1.25 / 1M tokens
Output price$4.25 / 1M tokens
Intelligence Score45
Coding index33.8

Quick answers

What is the context window of Muse Spark Open (Reasoning)?

Muse Spark Open (Reasoning) has a context window of 1M tokens, with a maximum output of 1M tokens per response.

How much does Muse Spark Open (Reasoning) cost?

Muse Spark Open (Reasoning) costs $1.25 per 1M input tokens and $4.25 per 1M output tokens through the API.

Is Muse Spark Open (Reasoning) open source?

Yes. Muse Spark Open (Reasoning) is an open model released under the open weights license.

When was Muse Spark Open (Reasoning) released?

Meta released Muse Spark Open (Reasoning) on October 15, 2026.

How does Muse Spark Open (Reasoning) compare to Claude Opus 5.5 (Reasoning)?

Muse Spark Open (Reasoning) scores 45 on the Intelligence Score versus 59.9 for Claude Opus 5.5 (Reasoning), the current #1. Input pricing is $1.25 vs $4 per 1M tokens.

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