Muse Spark Open at a glance.
From Meta's own pages, read Oct 20, 2026, so company-reported. A token is a word or part of a word. Prices can change; check the maker's page before you build on them.
- Made by
- MetaBased in US
- Released
- Oct 15, 2026Meta research blog: Muse Spark Open
- What it is for
- “The most capable US open-weight model to date. Build your way, anywhere.”Meta for Developers: models list, Oct 20, 2026 · in Meta's words
- Reads at once
- 1M tokensIts context window: how much text it can take in one go
- Takes in
- text, image, video, audio
- Download
- Yes, open weightsLicense: Muse Model License
- Size
- 816B parameters, 42B activeHugging Face model card meta-models/Muse-Spark-Open-816B-A42B, Oct 20, 2026
Meta doesn't sell it by the token: it's free to download, and hosting companies set their own prices.
Open-weight, self-hosted; no Meta Model API price listed.
Meta Model API docs: Pricing and rate limits, Oct 20, 2026 · company-reported
Where it ranks.
Its position on each of the 21 tests the models page uses, by testers other than the maker. Epoch AI's and Vectara's scores are shown under their open licenses; for LMArena, Scale and Vals we give the position and link to their own leaderboard. Each list is a snapshot with its date.
| Test | Rank | Score |
|---|---|---|
| Epoch Capabilities IndexEpoch AI, Oct 20, 2026 | Not in the top 30 | |
| Vals IndexVals AI, Oct 19, 2026 | Not in the top 20 |
| Test | Rank | Score |
|---|---|---|
| LMArena WebDevLMArena, Oct 19, 2026 | Not in the top 20 | |
| SWE-Bench ProScale AI, Sep 22, 2026 | #11 | On Scale AI |
| Vibe Code BenchVals AI, Oct 18, 2026 | Not in the top 20 | |
| LMArena coding chatsLMArena, Oct 15, 2026 | Not in the top 20 |
| Test | Rank | Score |
|---|---|---|
| LMArena textLMArena, Oct 15, 2026 | Not in the top 20 | |
| LMArena creative writingLMArena, Oct 15, 2026 | Not in the top 20 | |
| MultiChallengeScale AI, Feb 3, 2026 | Not in the top 15 |
| Test | Rank | Score |
|---|---|---|
| LMArena Agent ArenaLMArena, Oct 19, 2026 | Not in the top 20 | |
| Remote Labor IndexScale AI | Not in the top 16 | |
| Terminal-Bench 4.0Vals AI, Oct 19, 2026 | Not in the top 20 | |
| CUA-bench (games)Vals AI, Oct 13, 2026 | Not in the top 9 |
| Test | Rank | Score |
|---|---|---|
| LMArena mathLMArena, Oct 15, 2026 | Not in the top 20 | |
| Humanity's Last ExamScale AI | #11 | On Scale AI |
| ProofBenchVals AI, Oct 12, 2026 | Not in the top 20 |
| Test | Rank | Score |
|---|---|---|
| LMArena visionLMArena, Oct 19, 2026 | Not in the top 20 | |
| LMArena documentsLMArena, Sep 13, 2026 | Not in the top 20 |
| Test | Rank | Score |
|---|---|---|
| GPQA DiamondVals AI, Sep 1, 2026 | Not in the top 20 | |
| MMMU ProVals AI, Sep 1, 2026 | Not in the top 20 |
| Test | Rank | Score |
|---|---|---|
| Vectara hallucination testVectara, Oct 16, 2026 | Not in our copy of the list |
“Not in the top” means it isn't among the models in our copy of that list, which runs to the position shown; it may not have been tested. Vectara's test ranks by how rarely a model adds facts, so lower is better. Positions can be shared when scores tie. Epoch's range is its margin of uncertainty. Epoch AI and Vectara data: CC BY 4.0 and Apache-2.0.
Our note: Hugging Face card: 'Muse Spark Open is an 816B total/42B active parameter open weights model with a context window of 1M tokens.' Weights are gated (users must accept conditions). Research blog describes the license as having limited commercial terms. Meta's developer site still links Llama docs, but no new Llama model was found; Meta's current models are branded Muse.