New models· 1 min read
Meta releases Muse Spark Open, a very large open-weight model
Meta published the weights of Muse Spark, an 816-billion-parameter model that developers can download and run themselves under Meta's own license.
On October 15, 2026, Meta released Muse Spark Open, the downloadable version of its Muse Spark model from Meta Superintelligence Labs. Meta calls it the most powerful American open-weight model so far.
Key facts
- Size: 816 billion parameters in total, but only about 42 billion are active for each token. This mixture-of-experts design saves computing power.
- Context window: up to one million tokens.
- Where: the weights are on Hugging Face and the big cloud platforms, and several providers offer it through an API.
- License: it is open-weight, not fully open source. It comes under Meta's own Muse Model License, which includes limits on commercial use.
Why it matters
Open-weight models let schools, companies and researchers run AI on their own machines, keeping data private and costs under control. But “open” comes in shades, so always read the license. Learn more in Choosing the right model.
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