In short
How they differ.
Worked out from the figures below. Prices and specs are the makers' own, read Oct 20, 2026.
- Kimi K3 reads more at once: a context window of 1M tokens against 1M.
- Both can be downloaded and run on your own machine.
- On the 2 independent boards that rank both, each places higher on 1.
Side by side
The specs.
| Kimi K3 | Muse Spark Open | |
|---|---|---|
| Made by | Moonshot AI · China | Meta · US |
| Released | Not stated | Oct 15, 2026 |
| Price per 1M tokens | $3 in / $15 out | Free to download; hosts set prices |
| Context window | 1M | 1M |
| Takes in | text, image, video | text, image, video, audio |
| Download and run it yourself | Yes (Kimi K3 License) | Yes (Muse Model License) |
| Size | 2.8T parameters, 104B active | 816B parameters, 42B active |
| Maker says | “Kimi K3 is an open-weight, native multimodal agentic model and our most capable model to date.” | “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 | Kimi K3 | Muse Spark Open |
|---|---|---|
| Epoch Capabilities IndexEpoch AI, Oct 20, 2026 | #17157.42 | Not listed |
| LMArena textLMArena, Oct 15, 2026 | #18 | Not listed |
| LMArena coding chatsLMArena, Oct 15, 2026 | #12 | Not listed |
| LMArena WebDevLMArena, Oct 19, 2026 | #16 | Not listed |
| LMArena mathLMArena, Oct 15, 2026 | #16 | Not listed |
| Humanity's Last ExamScale AI | #14 | #11 |
| SWE-Bench ProScale AI, Sep 22, 2026 | #4 | #11 |
| Vals IndexVals AI, Oct 19, 2026 | #18 | Not listed |
| Vibe Code BenchVals AI, Oct 18, 2026 | #16 | Not listed |
| ProofBenchVals AI, Oct 12, 2026 | #12 | Not listed |
| GPQA Diamond (run by Vals AI, archived)Vals AI, Sep 1, 2026 | #12 | Not listed |
| MMMU Pro (run by Vals AI, archived)Vals AI, Sep 1, 2026 | #11 | Not listed |
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