Muse Spark Open

Muse Spark Open is Meta’s downloadable AI model for answering questions and taking actions through tools. Meta released the weights on 15 October 2026.

It reads several kinds of input and writes text

The model accepts text, images, audio and video and generates text, according to the Hugging Face technical guide. Its 1,048,576-token window is shared by the inputs and the conversation.

Muse Spark Open has about 816 billion total parameters, with about 42 billion active per token. A mixture-of-experts design selects part of the network for each step. The full model still needs substantial memory, including the inactive experts.

Developers can choose BF16 or NVFP4 checkpoints

Meta’s official collection provides BF16 and NVFP4 versions. Quantisation stores model values at lower precision to reduce memory use. Hardware, runtime and context length determine the full deployment requirements.

Hosted providers also offer access. Their prices and supported features belong to those providers and can differ from a self-hosted deployment.

The Muse Model License sets commercial conditions

Meta publishes the weights under the Muse Model License with limited commercial terms. Its announcement says many developers can use the model free of charge under those conditions. Teams planning a product should read the current licence and access terms before choosing a deployment.

The release gives developers the files needed to adapt and host the model. Its practical value depends on task success, hosting resources and the permissions attached to its tools.