Meta and Apple are working together to bring a powerful new open-weight AI model to high-end Macs.
Meta announced Muse Spark Open on Thursday, describing it as “the most capable US open-weight model to date.” For its part, Apple updated its MLX machine-learning framework for the model.
“Leveraging the latest version of MLX, Muse Spark Open was optimized to run on Mac Studio with M5 Ultra, and together they’re the best way to run a powerful model on your own desktop,” said Meta in a statement.
The importance of open-weight AI models
An open-weight AI model is a type of artificial intelligence whose core “building blocks” — the internal settings and patterns learned during training — are made freely available for anyone to use. Think of it like a recipe: instead of just letting you order a finished meal at a restaurant, the creators reveal the exact ingredients, measurements and cooking instructions.
By making these internal components accessible, open-weight models offer much greater transparency, allowing users to better understand how decisions are made by the AI.
And unlike AI services that depend on a company’s data servers, an open-weight AI model is available to download and run on the user’s own hardware.
Meta and Apple partner on Muse Spark Open
Meta’s new Muse Spark Open boasts 816 billion total parameters, although its architecture activates only about 42 billion parameters for a given processing step.
“Built for coding and agentic work, it excels at long-horizon tasks, complex software engineering, and multi-step reasoning,” says Meta.
Thanks to MLX, Muse Spark Open takes advantage of Apple silicon’s unified memory architecture. Two Mac Studio units, each with an M5 Ultra and 512 GB of RAM, can hold the entire model. And the chip’s 1.2 terabytes-per-second of memory bandwidth certainly helps. The two Macs communicate over high-speed Thunderbolt 5 connections.
“The result is two Mac Studios behave like one supercomputer with a terabyte of unified memory,” said Meta.
Mark Zuckerberg and John Ternus, the CEOs of Meta and Apple, congratulated each other on today’s news via X.
Congrats to the team! Amazing to run a model of Muse Spark Open's caliber and scale this efficiently, right from your desk. Mac Studio keeps pushing the boundaries of on-device AI!
— John Ternus (@johnternus) October 15, 2026
Muse Spark Open is available now
Meta released the weights for Muse Spark Open on Thursday.
The target audience is developers, researchers and businesses rather than ordinary Mac owners. The hardware needed to run Muse Spark Open locally is expensive, and installing a model of this size isn’t as simple as downloading a typical Mac app.
Still, Apple supporting Muse Spark Open helps make its high-end Macs valuable tools in the growing AI industry, even as the company continues developing its own AI features.
Ed Hardy has been writing full-time about tech for 26 years, and using it for much longer than that. His intro to Apple was a Macintosh SE/30 (which he still has), but now he uses a 13-inch iPad Pro as his primary computer.
That’s because he’s a “tablet first” type of guy. Rather than use a Macbook, he connects a keyboard case to the iPad. And instead of a desktop Mac, he connects his tablet to a 27-inch display and full-size keyboard. (So don’t try to tell him that everyone has to use a Mac to be productive.)
Before coming to Cult of Mac, Ed wrote for NotebookReview, TabletPCReview and Brighthand, as well as other sites.
