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Meta releases Muse Spark Open, an 816B-parameter open-weight model built with Apple

Meta says Muse Spark Open is the most capable US open-weight model, with 816 billion parameters and a 1 million token context, and runs locally on two Apple M5 Ultra Mac Studios.

Briefed from 4 sources1 min readUpdated Thu 22:23

In context

  • Meta calls Muse Spark Open the "most capable US open-weight model to date"; weights are on Hugging Face and the model is available through several API platforms.
  • The natively multimodal mixture-of-experts model has 816 billion total parameters and a 1 million token context window, and Meta says it excels at long-horizon tasks, software engineering and multi-step reasoning.
  • Meta says it is the first model in its class to run on a desktop, using two M5 Ultra Mac Studios with Apple's MLX framework. Engadget, per TechCrunch, reports it needs at least 1TB of RAM.
  • Meta and Apple developed the MLX support jointly over several months, per Axios. Zuckerberg and Apple CEO John Ternus praised the work publicly on X, and Apple published a technical post on MLX.
  • Meta says it paired the model with its Muse Code terminal for tasks such as fixes to a Mastodon client and reviewing and cropping footage in DaVinci Resolve.
Image: Hugging Face

Why it matters

Muse Spark Open follows Meta's Muse family, which also includes the separate Muse consumer agent app that launched last month and has drawn privacy criticism. Meta and Apple are usually rivals, so the joint launch is unusual. Open-weight releases at this scale let developers run and modify frontier-class models without relying on a hosted API.

Sources

  1. 01Welcome Muse Spark Open: open-weight frontier multimodal mixture-of-experts model from MetaHugging Face · Thu 02:00
  2. 02Friends don’t let friends feed their data to AI agentsThe Verge · Thu 18:21
  3. 03Meta and Apple team up to make Muse AI models run better on MacsThe Verge · Thu 20:15
  4. 04Meta launches an open-weight AI model that runs on MacsTechCrunch · Thu 22:04

This briefing was written by Claude from the sources above. Check the original reporting before relying on it.