In short
How they differ.
Worked out from the figures below. Prices and specs are the makers' own, read Oct 20, 2026.
- Muse Spark 1.3 reads more at once: a context window of 1M tokens against 1M.
- Muse Spark Open can be downloaded and run on your own machine; Muse Spark 1.3 can't.
- On the 1 independent board that rank both, Muse Spark Open places higher on 1 and Muse Spark 1.3 on 0.
Side by side
The specs.
| Muse Spark 1.3 | Muse Spark Open | |
|---|---|---|
| Made by | Meta · US | Meta · US |
| Released | Not stated | Oct 15, 2026 |
| Price per 1M tokens | $1.25 in / $4.25 out | Free to download; hosts set prices |
| Context window | 1M | 1M |
| Takes in | text, image, video, audio, pdf | text, image, video, audio |
| Download and run it yourself | No | Yes (Muse Model License) |
| Size | Not published | 816B parameters, 42B active |
| Maker says | “Muse Spark 1.3 is trained for agentic workflows and optimized for competitive coding performance.” | “The most capable US open-weight model to date. Build your way, anywhere.” |
| Sources | Prices, Oct 20, 2026 · Description | Prices, Oct 20, 2026 · Description |
Independent tests
Where they place.
Position on each board we follow (1 is best). Epoch AI's and Vectara's scores are shown; the other boards are linked for their own figures.
| Board | Muse Spark 1.3 | Muse Spark Open |
|---|---|---|
| Epoch Capabilities IndexEpoch AI, Oct 20, 2026 | #22156.76 | Not listed |
| LMArena textLMArena, Oct 15, 2026 | #10 | Not listed |
| LMArena coding chatsLMArena, Oct 15, 2026 | #15 | Not listed |
| LMArena WebDevLMArena, Oct 19, 2026 | #14 | Not listed |
| LMArena mathLMArena, Oct 15, 2026 | #11 | Not listed |
| LMArena visionLMArena, Oct 19, 2026 | #13 | Not listed |
| LMArena documentsLMArena, Sep 13, 2026 | #15 | Not listed |
| LMArena Agent ArenaLMArena, Oct 19, 2026 | #16 | Not listed |
| Humanity's Last ExamScale AI | #12 | #11 |
| SWE-Bench ProScale AI, Sep 22, 2026 | Not listed | #11 |
| Vibe Code BenchVals AI, Oct 18, 2026 | #14 | Not listed |
| CUA-bench (games)Vals AI, Oct 13, 2026 | #7 | Not listed |
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