Meta releases Muse Spark Open, an open-weight version of Muse Spark, under the Muse Model License

On October 15, 2026 Meta released Muse Spark Open, which its developer blog describes as the open-weight version of Muse Spark, trained for long-horizon agentic work such as coding and customer service agents. The model card lists 816B total and 42B active parameters, a context window of 1M tokens, text, image, video, and audio input, and text output; BF16 and NVFP4 checkpoints are on Hugging Face, and downloading them requires accepting the license conditions and submitting an access form. The weights are released under the Muse Model License, which requires a visible "Built with Muse Spark Open" attribution, incorporates a Usage Policy, and requires some large API providers to sign a separate agreement with Meta; the license does not describe itself as open source. USASI has not tested this model.123

USASI. (2026, October 16). Meta releases Muse Spark Open, an open-weight version of Muse Spark, under the Muse Model License. United States of America Superintelligence. https://unitedstatesofamericasuperintelligence.com/news/meta-releases-muse-spark-open-open-weight-model/

@misc{usasi_news_meta_releases_muse_spark_open_open_weight_model,
  author = {{USASI}},
  title = {Meta releases Muse Spark Open, an open-weight version of Muse Spark, under the Muse Model License},
  year = {2026},
  month = oct,
  howpublished = {\url{https://unitedstatesofamericasuperintelligence.com/news/meta-releases-muse-spark-open-open-weight-model/}},
  note = {United States of America Superintelligence. Last updated 2026-10-16}
}