Meta · Muse Spark (open weights) line · flagship · open weights
Muse Spark Open was released by Meta on October 15, 2026, as an open-weights flagship model in the Muse Spark (open weights) line.
Meta's first downloadable Muse Spark: an 816B-parameter mixture-of-experts model with about 42B active parameters, a 1M-token context and text, image, video and audio input, released under the Muse Model License.
Compared with GLM 5.3 · a competitor — comparison chosen by Meta
Completes more tool-using agent tasks than GLM 5.3
MCP-Atlas — agent tasks that call real tools through MCP servers
89.2
▲ vs 84.2 for GLM 5.3 · +5 points · Meta's table, Muse Spark Open at xhigh effort
Scores 39 on a combined set of hard tests
Artificial Analysis Intelligence Index v4.3.2 — one score averaging 10 hard tests
39
✦ Xhigh effort · first open-weights Muse Spark, nothing earlier to compare
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Muse Spark Open is the current model in this line. The card shows how long it has been since the last release against the line's usual gap and its recent ones — the rhythm, not a date.
Latest: Muse Spark Open · Oct 15, 2026
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