Meta announced Muse Spark Open on 15 October 2026. It is an open‑weight mixture‑of‑experts (MoE) model that can process text, images, audio and video in a single prompt. The model has about 816 billion total parameters, but only roughly 42 billion are active for each token, letting it run faster than a full‑size model of that scale. It also offers a massive context window of up to one million tokens, meaning long documents, codebases or video transcripts can be handled in one go.
What the model can do
Muse Spark Open is tuned for “agentic coding” – reading a codebase, writing or debugging code, and calling external tools while looking at screenshots, voice notes or screen recordings. It generates only text, but the input can be any combination of modalities. The model ships in two checkpoint formats: BF16 (about 1.5 TB) and a 4‑bit NVFP4 version that runs on NVIDIA Blackwell GPUs. Meta provides integration recipes for llama.cpp, vLLM, SGLang and other inference frameworks, plus a hosted Hugging Face Inference Endpoint that uses an OpenAI‑compatible API.
Why it matters
Developers can now run a single AI model that understands code, screenshots and voice notes without switching tools, potentially speeding up debugging and documentation tasks. However, the model still needs high‑end GPU hardware or a hosted endpoint, so it remains out of reach for casual users without such resources.
