Muse Spark
Meta's first closed frontier model — and its comeback story
Latest: Muse Spark 1.2 (Aug 5, 2026); 1.1 added 1M-token context + agentic gains (Jul 9, 2026)
MSL's first frontier model and Meta's first closed-weight flagship, launched April 8, 2026 — a natively multimodal reasoning model with tool use, visual chain of thought, and multi-agent orchestration. Offers Instant, Thinking, and Contemplating modes (the last orchestrates parallel reasoning agents), and now powers Meta AI across apps reaching billions of users.
Why it matters
Muse Spark ended Meta's open-weight era and took the company from also-ran to credible frontier contender in one release, reportedly matching Llama 4 Maverick with over an order of magnitude less compute. Version 1.3 shipped September 2, 2026, using about 20% fewer tool calls and 25% fewer tokens on agentic coding.
Facts
- Contemplating mode scores 58% on Humanity's Last Exam and 38% on FrontierScience Research.
- Debuted 4th on Artificial Analysis (behind GPT-5.4, Gemini 3.1 Pro, Claude Opus 4.6) but led HealthBench Hard 42.8 vs Gemini 3.1 Pro's 20.6.
- Matches Llama 4 Maverick with over an order of magnitude less compute.
- Built with 1,000+ physician collaborators and trained on Meta's new AI superclusters.
- A 1.1 update shipped just three months later.
Try it yourself
Use it via OpenRouter (Muse Spark 1.3) ↗ Meta Model API docs ↗ Chat at meta.ai ↗
Lineage
Sources
Meta AI blog · introducing muse spark msl ↗Meta AI blog · introducing muse spark meta mo ↗Meta Newsroom ↗Wikipedia ↗TechCrunch ↗CNBC ↗