Meta MPK 15, 1, Hacker Way, 1 Hacker Way, Belle Haven, Menlo Park, San Mateo County, California, 94025, United States
Meta
Meta's[1][2] post is dated "September 2, 2026" and says "We're excited to release Muse Spark 1.3" and that it "is available today in Muse Code and in Meta Model API"; Artificial Analysis[4]' write-up of the same day opens "Meta has released Muse Spark 1.3".
Meta releases Muse Spark 1.3, its fourth Muse Spark model in five months, trained for long agentic and coding work and still priced at $1.25 per million input tokens; Artificial Analysis ranks its top variant behind only Anthropic's Claude Fable 5.1 and Opus 5.