# Muse Spark Open

> Muse Spark Open is an open-weight language model from Meta, released on 15 Oct 2026. It accepts text, images, video, PDFs and audio and generates text, with a 1M-token context window and up to 944K output tokens per response. As of 17 Oct 2026, the lowest listed API price is $1.25 per million input tokens and $4.25 per million output tokens (Fireworks AI), across 4 providers we track.

Source page: https://www.aimodel.directory/models/muse-spark-open
Last verified: 17 Oct 2026

## Specifications

- **Developer:** Meta
- **Release date:** 15 Oct 2026 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/meta/muse-spark-open.toml)
- **Status:** Generally available (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/meta/muse-spark-open.toml)
- **Weights:** Open weights (source: Hugging Face, https://huggingface.co/meta-models/Muse-Spark-Open-816B-A42B)
- **License:** muse-model-license (source: Hugging Face, https://huggingface.co/meta-models/Muse-Spark-Open-816B-A42B)
- **Parameters:** 822B (source: Hugging Face, https://huggingface.co/meta-models/Muse-Spark-Open-816B-A42B)
- **Context window:** 1M (1,048,576 tokens) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/meta/muse-spark-open.toml)
- **Max output:** 944K tokens (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/meta/muse-spark-open.toml)
- **Knowledge cutoff:** 4 Jan 2026 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/meta/muse-spark-open.toml)
- **Input:** Text, images, video, PDFs and audio (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/meta/muse-spark-open.toml)
- **Output:** Text (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/meta/muse-spark-open.toml)
- **Reasoning mode:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/meta/muse-spark-open.toml)
- **Tool calling:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/meta/muse-spark-open.toml)
- **Structured output:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/meta/muse-spark-open.toml)
- **Hugging Face:** meta-models/Muse-Spark-Open-816B-A42B (source: Hugging Face, https://huggingface.co/meta-models/Muse-Spark-Open-816B-A42B)

## API pricing (USD per 1M tokens)

| Provider | Input | Output | Cached input | Context |
|---|---|---|---|---|
| Fireworks AI | $1.25 | $4.25 | $0.15 | 1M |
| Nebius AI Studio | $1.25 | $4.25 | $1.25 | 1M |
| OpenRouter | $1.25 | $4.25 | $0.15 | 1M |
| Vercel AI Gateway | $1.25 | $4.25 | $0.15 | 1M |

## FAQ

### What is the context window of Muse Spark Open?

Muse Spark Open has a context window of 1,048,576 tokens (1M) and can generate up to 943,718 tokens in a single response, according to models.dev.

### How much does the Muse Spark Open API cost?

Muse Spark Open is listed from $1.25 per million input tokens and $4.25 per million output tokens (Fireworks AI). Prices last verified 17 Oct 2026.

### Is Muse Spark Open open source?

Muse Spark Open is an open-weight model: its weights are published on Hugging Face as meta-models/Muse-Spark-Open-816B-A42B under the muse-model-license license. Check the license terms before commercial use.

### When was Muse Spark Open released?

Meta released Muse Spark Open on 15 Oct 2026, according to models.dev.

### Which providers offer Muse Spark Open?

We track Muse Spark Open on 4 providers: Fireworks AI, Nebius AI Studio, OpenRouter, Vercel AI Gateway.

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Data licensed CC BY 4.0. Cite as: AI Model Directory, "Muse Spark Open", https://www.aimodel.directory/models/muse-spark-open