Meta · llm model

Muse Spark Open

Muse Spark Open is Meta's latest language model in our dataset, released Oct 15, 2026. Open weights (Muse Model License (limited commercial terms)). Meta's open-weights 816B-parameter mixture-of-experts model (42B active), released Oct 15, 2026 under the Muse Model License, which has limited commercial terms. Verified against vendor sources on Oct 26, 2026.

Reported Last verified Oct 26, 2026 · All models · JSON · Markdown

ReleasedOct 15, 2026
Context window1M1,000,000 tokens
LicenceOpen weights, restrictedMuse Model License (limited commercial terms)

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Key facts

Muse Spark Open: key facts with sources
Fact	Value	Source
Vendor	Meta	n/a
Released	Oct 15, 2026	source
Status	generally available	n/a
Context window	1,000,000 tokens (1M)	source
Input	text, image, video, audio	source
Output	text	source
Parameters	816B total, 42B active, mixture-of-experts, 256 experts, 8 active	source
Licence	Muse Model License (limited commercial terms) (open weights) Not an OSI-approved open-source license; read the terms before commercial use.	source

Where Muse Spark Open sits in our data

Released Oct 15, 2026 (week 42 of 2026), in October 2026. Other models in our data released that month: GPT-6.1 Terra, Kimi K3.1 Pro, Kimi K3.1 Pro Highspeed, Nemotron 3.5 Bolt E4B (4GB), Voxtral 3, Mercury 3.
The previous Meta model we track is Muse Wonder Full (Oct 12, 2026), 3 days earlier.
Of the 60 models in our data with a published context window, Muse Spark Open has the number 23 largest (1M tokens). Our data is not every model on the market.
All releases by date: AI model releases by month · new AI models this week. Choosing for code: best LLM for coding.

How Muse Spark Open differs from Muse Wonder

Read from the recorded facts of the two models, not from a head-to-head test. We have not run either.

We have no recorded price for Muse Spark Open; Muse Wonder has one.
Context window is 1M tokens against 1.05M for Muse Wonder.
Input is text, image, video, audio, against text, image, video, audio, pdf for Muse Wonder.
Status is generally available, against public preview.
Muse Spark Open came out 3 days after Muse Wonder.
Facts for the other model: Muse Wonder.

What the sources say

These are claims from the linked pages, not our measurements.

Needs about 700 GB of VRAM for the NVFP4 checkpoint and about 2 TB for BF16, per Meta; it is not a laptop model.

Notes

Meta lists hosted access at Baseten, Fireworks, Groq, Modal, Nebius, OpenRouter and Together; prices are set by those providers.

What we tested

Nothing yet. We have not run Muse Spark Open ourselves, so every fact on this page is Reported from the sources below. When we do test it, the scope will be stated here and in our test logs. See methodology.

Not verified, left out

We could not confirm these on a vendor page, so we do not state them.

Meta's own API price: not stated by Meta. Meta's proprietary Muse Spark 1.x models appear on public leaderboards but we did not verify their specifications; Muse Wonder is listed separately.