Meta · Open Weight Frontier

Muse Spark Open

Meta's first open-weight member of the Muse Spark family, released 15 October after the API-only Muse Spark releases up to 1.3 (covered in week 36). It is a natively multimodal mixture-of-experts model with 816B total and 42B active parameters and a 1M-token context, aimed at coding and agentic work. Weights are on Hugging Face (manually gated), SageMaker, Google Cloud Model Garden and Microsoft Foundry, with hosted access through OpenRouter, Together, Groq, Fireworks and others, and support in SGLang, vLLM, TensorRT-LLM, MLX, llama.cpp and Unsloth; Meta says it runs on two M5 Ultra Mac Studios. Released under the Muse Model License with limited commercial terms. Meta calls it the most capable US open-weight model but publishes no benchmark numbers yet.