Meta has released Muse Spark Open, an 816B-total / 42B-active Mixture-of-Experts model with a 1 million token context window. This model is designed for coding, long-horizon agents, and multi-step reasoning, accepting text, image, video, and audio inputs. While it leads among US open-weight models on some benchmarks, it lags behind competitors like GLM-5.3 and Kimi K3 in agentic evaluations. The model is available under a custom license that includes attribution requirements and a separate agreement for certain commercial uses. AI
IMPACT Sets a new benchmark for open-weight models in context window length and multi-modal capabilities, potentially influencing future research and development.
RANK_REASON Frontier-lab model release with system card. [lever_c_demoted from frontier_release: ic=1 ai=1.0]
- Artificial Analysis
- Baseten
- DeepSeek V4.1 Flash
- Fireworks
- GLM 5.3
- Goodfire
- Kimi k3
- Meta
- Muse Model License
- Muse Spark Open
- Nathan Lambert
- Nick Cammarata
- Spark 1.3
- Together
- vLLM
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