Meta released Muse Spark Open, an AI model with 816 billion total parameters, on October 15, 2026. The model became available through Arena.ai's Agent Arena and Code Arena for developer testing on launch day. Meta designed the model for long-horizon agentic workflows, complex coding tasks, and multi-step reasoning. This marks the first open-weight release from Meta's Muse Spark series, which previously consisted of proprietary models. The model supports multimodal inputs including images, video, and audio, with a 1 million-token context window.
Meta Releases 816B-Parameter Muse Spark Open Model
Muse Spark Open contains 816 billion total parameters, with 42 billion active parameters. The model operates with a 1 million-token context window and accepts images, video, and audio as inputs.
Meta positioned the model for three specific use cases: long-horizon agentic workflows, complex coding, and multi-step reasoning. For coding applications, Meta stated the model supports analyzing entire repositories and handling complicated refactors across multiple files.
Meta Superintelligence Labs claimed Muse Spark Open matches frontier closed models on agentic coding benchmarks.
Muse Spark Open Available Through Multiple API Providers
Muse Spark Open became available on October 15, 2026, through multiple API platforms and cloud marketplaces. API access operates through providers including Baseten and Fireworks AI.
Teams can download the model weights from Amazon SageMaker and Google Cloud Model Garden. Meta stated the model can run on user infrastructure, with specific optimization for Apple silicon through the MLX framework. The reference setup consists of two M5 Ultra Mac Studios configured together as a supercomputer with 1TB of unified memory.
Meta stated the model underwent safety post-training, which according to Meta allows Muse Spark Open to operate on a standalone basis without external guardrails.
Arena.ai Integrates Model for Live Developer Testing
Arena.ai confirmed the integration of Muse Spark Open into Agent Arena and Code Arena on launch day. Users can test the model on complex tasks and score its performance in these platforms.
Agent Arena and Code Arena apply models to practical tasks involving coding, web search, and multimedia processing. The platforms provide live scoring showing model performance.
Muse Spark Open builds on Meta's earlier Muse Spark models, which were proprietary. This release represents the series' first move into open weights.
FAQ
What did Meta release on October 15, 2026?
Meta released Muse Spark Open, an AI model with 816 billion total parameters and 42 billion active parameters. The model supports multimodal inputs including images, video, and audio, with a 1 million-token context window. This represents the first open-weight release from Meta's Muse Spark series.
Where can developers access Muse Spark Open?
Developers can access Muse Spark Open through multiple API providers including Baseten and Fireworks AI. Teams can download model weights from Amazon SageMaker and Google Cloud Model Garden. Arena.ai integrated the model into Agent Arena and Code Arena for live testing on launch day.
