Meta · Language model

Muse Spark Open

Meta's open-weight Muse model: 816 billion parameters, 42 billion active, with a 1M-token context window. Meta calls it the most capable US open-weight model yet.

MakerMeta
ReleasedOctober 15, 2026
API price (per 1M tokens)Not published
Open weightsYes

Best for

  • Self-hosting
  • Tool-calling agents
  • Teams that need a US-made open model

Strengths

  • Leads GLM-5.3 and Kimi K3 on MCP-Atlas tool use in Meta's own table
  • Weights on Hugging Face, Amazon SageMaker, Google Cloud and Microsoft Foundry
  • 1M-token context

Watch out for

  • Trails GLM-5.3 and Kimi K3 on the Artificial Analysis index (39 vs 45 and 44 in Meta's table)
  • Custom Muse Model License, not Apache or MIT
  • 816B parameters needs serious hardware

Ranking history

EditionPower RankingsCodingBest ValueOpen-Weight WatchImage GenerationVideo Generation
Week 45, 2026———#5 (84)——
Week 44, 2026———#4 (85)——
Week 43, 2026———#3 (85)——