Rohan Paul

After years of rivalry, Meta and Apple join hands to deliver open-weight AI to the Mac. Meta released the weights for Muse Spark Open, an 816B-parameter model that runs on 2 linked Mac Studios. Apple tuned the release for its MLX framework. Only 42B parameters fire per token because the model routes each token to 8 of 256 experts, so every step reads a small slice of memory. Holding the whole model is the hard part, since the 4-bit NVFP4 version needs at least 700GB of GPU memory. Each M5 Ultra Mac Studio gives its GPU up to 512GB of unified memory, so 2 machines hold the model while 1.2TB/s of bandwidth feeds each token. On the benchmarks, Muse Spark Open does top the MCP-Atlas tool-use test at 89.2, which suits the coding agents Meta built it for. The license allows free commercial use but requires a “Built with Muse Spark Open” label, plus a separate Meta deal for API model sellers with over $20M in 12-month revenue. Apple hasn’t priced the 512GB Mac Studio, and a cluster of 4 machines with 256GB each costs roughly $38,000.