Meta releases Muse Spark Open: it runs on two Mac Studios, and its license bans passing off its output as human-written
Meta released Muse Spark Open, an 816-billion-parameter open-weight model that runs on two Mac Studios and forbids presenting its output as human-written.Summary
On October 15, 2026, Meta released the weights of Muse Spark Open, the open version of its Muse Spark model. It has 816 billion parameters, 42 billion of them active per token, a one-million-token context window, and accepts text, images, video and audio. Meta calls it "the most capable US open-weight model to date," built for coding and agentic work. The license permits free commercial use, but requires a "Built with Muse Spark Open" notice and bans presenting the model's output as human-written. Through the API it costs the same as the closed Muse Spark: $1.25 per million input tokens and $4.25 per million output tokens. The weights are available on Hugging Face, Amazon SageMaker AI, Google Cloud Model Garden and Microsoft Foundry, with six hosts already serving it via API. All 816 billion parameters must stay loaded in memory: roughly 1.65 TB for BF16 and 537 GB for NVFP4, requiring at least 700 GB of GPU memory, or two Mac Studios with M5 Ultra chips and 512 GB each running MLX. Meta's published benchmarks compare Muse Spark Open only with other open models, where it leads on MCP-Atlas and JobBench but trails Kimi K3 on coding tests. Open questions remain, including a forthcoming safety report and how the "Built with" notice applies to customers who only call a host's API.
(Source：MACCUS - SEO, Influence & Organic Marketing Agency)