Meta releases Muse Spark Open, an 816B open-weight model

Meta Superintelligence Labs has published the weights of Muse Spark Open, a mixture-of-experts model with 816 billion parameters, about 42 billion of which activate per token. It scores 39 on the Artificial Analysis Intelligence Index and supports a 1M-token context. Hosted APIs charge a median of $1.25 per million input tokens and $4.25 per million output tokens.

• 816B parameters, roughly 42B active per token
• Scores 39 on Artificial Analysis, top US open-weight model
• 1M-token context aimed at coding and agentic tasks
• Muse Model License requires attribution and a $20M revenue clause