Muse Spark Open is Meta’s open-weight multimodal AI model released on October 15, 2026. It has 816 billion total parameters with 42 billion active at a time (a mixture-of-experts design), a 1-million-token context window, and accepts text, image, video, and audio input with text output. Meta describes it as the most capable U.S. open-weight model to date, aimed at coding and agent-style work, and says it can run on two Apple Mac Studios with M5 Ultra chips.
Developers can download the weights from platforms such as Hugging Face and run them with engines including SGLang, vLLM, and Apple MLX. Meta released the weights under the Muse Model License with limited commercial terms.
Source: Meta AI Research — Introducing Muse Spark Open (October 15, 2026).