Meta Releases Muse Spark Open. Apps That Use It Must Say So.

The 816-billion-parameter coding model is free for many developers, but big AI-hosting businesses must sign a separate deal with Meta.

Meta posted a new AI model for download Thursday, and its X account called Muse Spark Open "the most capable US open-weight model to date."

Open-weight means the trained model itself, all 816 billion parameters of it, can be downloaded and run on machines the developer controls. Meta's announcement says it's built for coding and agent work, and that it's available now on Hugging Face and the model stores run by Amazon, Google and Microsoft, plus seven hosted services including Groq and OpenRouter. The pitch is freedom. The model card and license, both posted alongside it, spell out how much.

Meta's announcement says people should be able to run strong models anywhere, "including at home." The home Meta has in mind holds two Mac Studios with Apple's M5 Ultra chip. Each one can give its graphics up to 512 gigabytes of memory, and Meta says that's enough for the pair to hold the whole model. The alternative, according to the model card on Hugging Face, is a GPU setup with at least 700GB of video memory for the smaller NVFP4 version, or 2TB for the full BF16 one.

Meta says it ran real jobs entirely on those Macs using its Muse Code tool. By Meta's account, the model shipped bug fixes and new features to Ice Cubes, an open-source Mastodon app, and cut video in DaVinci Resolve by picking the strongest moments and cropping them vertically. That's the company describing its own test.

The "US" in the slogan matters. On the broadest score in Meta's own benchmark table, the Artificial Analysis Intelligence Index, Muse Spark Open gets 39. GLM 5.3 gets 45, Kimi K3 gets 44 and a Qwen model gets 40. Meta's table does put its model first on other tests, including an agent benchmark called MCP-Atlas, where it scores 89.2.

Then there's the Muse Model License. Any product or service that uses the model, or any model fine-tuned or distilled from it or from its outputs, must "prominently display 'Built with Muse Spark Open'" in its interface, documentation, website or settings menu.

The bigger catch is for companies that sell AI. If a business offers models to others through an API, and it and its affiliates gross more than $20 million in any 12-month stretch, it has to notify Meta and sign a separate agreement before serving Muse Spark Open. A company that keeps the model in-house, studies it, or wires it into its own app instead of reselling it as a model service is exempt from that clause. That's what Meta's blog means when it says "limited commercial terms" let many developers use the model for free.

Even the download has a form. The Hugging Face page won't hand over the files until a person supplies a date of birth, a full legal name and the complete name of their organization, corporate identifiers and all. It warns that the answers can't be changed after submission.

Meta says the open version got extra safety training so it holds up against misuse when it runs alone, and the model card tells developers to add their own guardrails. The license says who's on the hook. Meta disclaims liability for anything built from the model, and the developer is "solely responsible for the safety, deployment, and use" of it. Meta says a full evaluation report is on the way.

Meta's announcement ends by asking builders to share what they make on Hugging Face's forums, saying it would love to see it. Under the license, anyone who ships something with it will be telling their users anyway.

Source: X, retrieved October 16, 2026. Other sources: research.meta.ai, huggingface.co.