Meta releases Muse Spark Open, saying it is the most capable US open-weight model, with 816B total and 42B active parameters and a 1M-token context window

Muse Spark Open is available today and brings leading agentic capabilities to your desktop for the first time on Apple M5 Ultra Mac Studios.

Meta AI Research 2026-10-16

Context & Ripple Effects

Muse Spark began as a model used inside Meta AI, including its shopping mode, while Meta signaled an eventual open-source release in April. The August release of Muse Glimmer and a promised open Spark variant made this a staged move from internal product infrastructure toward external distribution.

The Apple collaboration gives that distribution a specific local deployment target: M5 Ultra Mac Studios. It also extends Meta's earlier plan to open-source a version of Muse Spark beyond consumer-facing Meta AI features to coding and agentic workloads.

First-order effects

Developers gain access to Muse Spark Open's weights and long-context model for local coding and agentic work on Apple M5 Ultra Mac Studios.
Apple gains a named, large-model desktop workload, while Meta puts a model previously associated with Meta AI and shopping into third-party hands.

Second-order effects

M5 Ultra Mac Studio buyers and enterprise developers can evaluate agentic workloads without making Meta AI their application layer, shifting differentiation toward local hardware, deployment tooling, and support.
Meta's internal use of Muse Spark gives it a continuing product channel even as open weights broaden the model's developer distribution.

Third-order effects

If major model developers pair open weights with optimized local hardware targets, the competitive unit shifts from access to model APIs toward the surrounding deployment stack and proprietary product integrations.
The release adds to a commercialization pattern in which open-weight models serve as complements to hardware and owned services rather than standalone revenue products.

The trend: Frontier-model vendors are increasingly using open weights to expand ecosystem adoption while retaining proprietary applications and deployment advantages.

Discussion

@finkd Mark Zuckerberg on x
Muse Spark Open — weights releasing today — runs great on new Mac Studios thanks to work with @johnternus and Apple.
@johnternus John Ternus on x
@finkd Congrats to the team! Amazing to run a model of Muse Spark Open's caliber and scale this efficiently, right from your desk. Mac Studio keeps pushing the boundaries of on-device AI!
@teortaxestex @teortaxestex on x
Muse Spark Open is substantially weaker than Spark 1.3 What gives? Is Spark 1.3 a much bigger model, or just non-nerfed?
@xlr8harder @xlr8harder on x
@natolambert hey they managed to get themselves to drop the absurd derivative model naming requirement from llama era. some serious progress here!
@haihaoshen Haihao Shen on x
Day-0 support Muse Spark, a strong open model from US. Congrats! https://research.meta.ai/... https://www.intel.com/... https://github.com/... https://github.com/... @IntelAI @huggingface @Meta
@digitalix Alex Ziskind on x
What's this? New model gonna need these bad boys. Meta's 816B param Muse Spark is open wieghts 🤯 1M-token context window. And MoE, so likely relatively fast. Now I'm really curious what my cluster can do!
@yuchenj_uw Yuchen Jin on x
love that Meta open-sourced Muse Spark Open! it's ~Muse Spark 1.2 level. my biggest wish: Meta follows up with Muse Spark 1.3 open weights. that would be the best OSS model in the world.
@skasriel Stephane Kasriel on x
This is a big deal. Can't wait to see how the community uses this model and fine tunes it with their own data to build next generation AI applications.
@badlogicgames Mario Zechner on x
meta going scorched earth in this economy https://research.meta.ai/...
@aiatmeta @aiatmeta on x
To help make advanced models more accessible, Muse Spark Open is optimized to run on two Apple M5 Ultra Mac Studios with the latest MLX framework. It also runs on leading inference engines like SGLang, vLLM, TensorRT-LLM, Hugging Face Transformers, llama.cpp, and Unsloth with opt…
@beffjezos @beffjezos on x
Meta just keeps winning. Ended up teaming up with Apple too!!! Beginning of the Golden Age of Local Superintelligence
@ccatalini Christian Catalini on x
Unlike the labs, Meta doesn't need to sell intelligence to win. It just needs to make it useful to a few billion people. https://x.com/...
@levie Aaron Levie on x
They did it. They made a Muse open weights model, which is a huge step forward for OSS in the US. This is going to further accelerate AI diffusion because enterprises will be able to mix and match frontier performance for orchestration and high end tasks, while being able to ha…
@bubbleboi Bubble Boi on x
Let's gooo
@garrytan Garry Tan on x
Open weight models rising
@clementdelangue Clem on x
llama serve -hf ggml-org/Muse-Spark-Open-816B-A42B- GGUF:Q2_K (on two mac studios). Well done @finkd & @johnternus!
@groqllc @groqllc on x
Muse Spark Open from @AIatMeta is now in limited preview on GroqCloud, running at 350+ tokens/sec per user. Meta trained it for agentic coding. It has 816B parameters (42B active). On GroqCloud, it supports 131,072 tokens of context and text and image input, with text output. Rea…
@mehulmpt Mehul Mohan on x
question is who's gonna host it cheaper than deepseek
@ekzhang1 Eric Zhang on x
In case like me you're wondering how you can fit a trillion parameters (usually $500k …
@alexandr_wang Alexandr Wang on x
3/ muse spark open is available today through API platforms at Baseten, Fireworks AI, Groq, Modal, Nebius, OpenRouter and Together AI. model weights are available for download on Amazon SageMaker AI, Google Cloud Model Garden, Hugging Face, and Microsoft Foundry Model Catalog. it…
@alexfinn Alex Finn on x
America is SO back Zuck just announced Muse Spark Open is dropping later today, built with Mac Studios in mind This is bigger than you think The Meta Muse model was trained specifically for agent tasks. Now we can run it locally, plugged into agents like Hermes This is the future…
@xlr8harder @xlr8harder on x
wow he's not kidding. they managed to make the llama 3.1 license worse complete trash zuck will not save you, open source users.
@aiatmeta @aiatmeta on x
Today we're releasing Muse Spark Open, the most capable US open-weight model to date. Built for coding and agentic work, it excels at long-horizon tasks, complex software engineering, and multi-step reasoning. Key Model Specs: → 816B total / 42B active parameters → 1M token conte…
@elder_plinius @elder_plinius on x
WTF IS THIS 🤬
@pratanchandani Prashant Ratanchandani on x
Every time I meet people to talk about the Muse family of models, one of the questions has been when we will release weights. The wait is over. Muse Spark Open is now available. The most capable US open weights model.
@alexandr_wang Alexandr Wang on x
muse spark open. why 2026 won't be like 1984 
@clementdelangue Clem on x
Meta is back! https://huggingface.co/...
@davis7 Ben Davis on x
I'm starting to really, really like Meta
@eliebakouch Elie on x
another major american lab doing hybrid sliding window attention :)
@ollama @ollama on x
Amazing to see @AIatMeta launch the best US open-weight model so far! The model will be available on Ollama shortly. 🫡
@natolambert Nathan Lambert on x
Okay now I really gotta blog 🎉
@natolambert Nathan Lambert on x
If it performs roughly what like the scores indicate, adoption of this model is going to go gangbusters. First open-weigh model in the US with near frontier agentic capabilities (GLM 5.2 + Kimi K3 was that step change from China). US models get crazy adoption.
@mattdeitke Matt Deitke on x
We're open-sourcing Muse Spark Open! This is an important release which is the most capable US open-weight model yet. 🇺🇸 - 816B parameters (42B active) - 1M token context window - Built for coding and long-horizon agents - Runs locally on two Apple M5 Ultra Mac Studios More here:…
@michaeldell Michael Dell on x
Customers love choice! @AIatMeta Muse Spark Open and @nvidia Nemotron 3.5 Super VL are now available on the Dell Enterprise Hub with @huggingface 🤗 https://dell.huggingface.co/ ...
@tokengremlin @tokengremlin on x
This is a brilliant release for those of us who love open source. The more, the better. But it also shows just how far ahead Chinese AI labs have gotten compared to the US, and I'm excited to see what they can pull off by distilling Opus 5.5 and GPT-6 Astra.
@natolambert Nathan Lambert on x
The Meta Muse Open License is trash. Thankfully no one really cares about licenses, expect the inference providers who will happily comply.
@armandjoulin Armand Joulin on x
congratulations @AIatMeta this is amazing to see you back in open model space with such an amazing model!
@iam_rajuptvs Raju Penmatsa on x
huge! congrats on the launch! I think this is a great move, and hope more follow.. releasing older model weights after launch of newer model. Hope this trend continues.
@kimmonismus @kimmonismus on x
Meta is so back! They are finally releasing Meta Muse Spark open weight. Best US open weight model 816B total / 42B active parameters 1M token context window Natively multimodal across text, image, video, audio Love to see!
@edwardsun0909 Zhiqing Sun on x
Muse Spark Open was literally as good as the best model we released just two months ago. Now it's open-weight. Enjoy! https://research.meta.ai/... [image] [embedded post]
@scaleailabs @scaleailabs on x
Congratulations to @AIatMeta on releasing Muse Spark Open. An incredible achievement and an exciting step toward a future with more choice in AI. The @Muse family has been especially strong on multi-step coding workflows, and open weights make it much easier to tune those capab…
@bscholl Blake Scholl on x
Mark has been on an epic multi-decade quest to found a new business inside Meta, one that he didn't acquire. No matter what happens he just keeps making bold bets. Stay in the game long enough and eventually you win. Mad respect. [embedded post]
@natolambert Nathan Lambert on x
@xlr8harder Its got all the restrictions across all license eras 1. Built with muse branding nonsense that no one followed 2. Revenue gate like kimi/glm (reasonable) 3. Restricted domains / authorized use policy 4. All of the above applies to models trained on ai outputs (maybe)
@almmaasoglu Alim on x
Meta is so unbelievably back and they made me eat my own words. I didn't expect them back so fast
Allen Bolourchi, PhD, MBA Allen Bolourchi, PhD, MBA on linkedin
Excited to share the release of Muse Spark Open, our best open-weight model at Meta and the most capable US open-weight model! …
Tatyana P. Tatyana P. on linkedin
Muse Spark Open! Many people were eagerly awaiting this release! It is the most capable U.S. open weight model to date built for coding, agentic, and natively multimodal. https://lnkd.in/gB8SS9t3 …
Hyung Won Chung Hyung Won Chung on linkedin
We have one more launch this week: Muse Spark Open! — Open weights, 816B total parameters, 42B active. This is a good model. …
Chenyang Zhao Chenyang Zhao on linkedin
Meta? Finally back with a new open-weight model, Muse Spark OSSed. — 816B total parameters, 42B active, 1M context, native multimodal capabilities …
Ash Jhaveri Ash Jhaveri on linkedin
Today we released Muse Spark Open with a large and diverse set of ecosystem partners to ensure developers can access the best western open model on their platform of choice, including running locally. …
Annie Hu Annie Hu on linkedin
Try Muse Spark Open!! It's been a Wonder(full) week! :)
Tatyana P. Tatyana P. on linkedin
Muse Spark Open! Many people were eagerly awaiting this release! It is the most capable U.S. open weight model to date built for coding, agentic, and natively multimodal. https://lnkd.in/... …
Sidhartha Reddy Potu Sidhartha Reddy Potu on linkedin
Muse Spark Open is out today: the most capable US open-weight model to date, from Meta Superintelligence Labs. …
Saurabh Baji Saurabh Baji on linkedin
Muse Spark Open is here - the most capable US open-weights model! — Strong agentic performance — 816B total / 42B active params — 1M context …
Mahesh Pasupuleti Mahesh Pasupuleti on linkedin
Another Muse release this week and this time its a open weight model - 816B parameters (42B active), 1M-token context window, natively multimodal across text, image, video and audio. …
@sungkim Sung Kim on bluesky
Meta released the open weight of Muse Spark Open — Muse Spark Open is an 816B total/42B active parameter open weights model with a context window of 1M tokens. — Blog: research.meta.ai/blog/muse-sp...
@eriskii.net Eris on bluesky
Muse spark is out now and it mogs every other open weight model — research.meta.ai/blog/muse-sp... [image]
@aaronp613 Aaron on x
So weird to see John Ternus and Zuck interacting on X
@beffjezos @beffjezos on x
John Ternus making moves. Very smart play here to compete with Nvidia / Nemotron
@viticci Federico Viticci on x
yeah, safe to say we're entering a new Apple era indeed
@divestech Dan Ives on x
We believe this could just be the start of Meta and Apple on the AI partnership front @CNBCFastMoney 🍿📺🏆🔥🍎📱
@anantn Anant Narayanan on x
Muse Spark Open weights available today! (And 👌 use of the Muse mac app) https://huggingface.co/... [embedded post]
@avichal Avichal Garg on x
The CEOs of @Apple and @Meta are tweeting about how efficient it is to run inference on Mac Silicon Someone should really build a distributed inference network that runs on top of Mac Silicon. It's probably a $10b company or protocol. 🙃
@shshnkp Shashank Prasanna on x
Today we also published benchmarks and a deep dive into LLM inference on M5 Ultra Mac Studio, covering MLX, GPU Neural Accelerators, tensor and pipeline parallelism, and Thunderbolt 5 RDMA. https://machinelearning.apple.com/ ... [embedded post]
@stammy @stammy on x
meta is just teasing us that they have prerelease M5 Ultra 512GB unified memory Mac Studios https://research.meta.ai/...
@viticci Federico Viticci on x
Meta has released the weights of Muse Spark Open, the most capable U.S. open-weight model to date. Apple worked closely with them to make it work with MLX and RDMA across multiple M5 Ultra Mac Studios. Details: https://www.macstories.net/...
@mweinbach Max Weinbach on x
Meta worked with Apple on optimizing MLX for this, including native multimodal support in mlx-lm and optimizations to MoEs and thunderbolt clustering It should get roughly 20 tokens per second on 2 M5 Ultra but I'm sure that could get way better
@trebolloc Ronan Collobert on x
So proud of the MLX team! Muse Spark Open, on your desk: 816B params at 36+ tokens/sec on 4 Mac Studio computers. We've been hard at work on better M5 GPU Neural Accelerator support, a smoother Thunderbolt experience (including multi-cable meshes), and kernel optimizations for Mo…
@fitz_keith Keith Fitz-Gerald on x
I suggested a while back that $AAPL would bring AI down to the device level first... so this of great. But not crazy about the fact that it is $META Muse I understand Muse is amazing, it's Zuck I don't trust. 🤷‍♂️ https://www.cnbc.com/...
@bubbleboi Bubble Boi on x
Meta released a model that runs better on apple silicon than apple. [embedded post]
@asherdipps Asher on x
@johnternus @finkd This looks like 2 AIs talking to each other lmfao
@mehulmpt Mehul Mohan on x
M5 Ultra (and beyond) might be the future of local AI
@bzamayo Benjamin Mayo on x
Nvidia, Netflix, now Meta ... Apple really is putting old feuds to rest https://x.com/...
@mattdeitke Matt Deitke on x
Muse Spark Open is live on @huggingface! 🤗 - Strong agentic model (especially for personal agents) - Multimodal from the ground up - 816B parameter model - 42B Active parameters Models link: https://huggingface.co/... [image]
@chancehmiller Chance Miller on x
Zuckerberg having to use X to thank Ternus because Apple doesn't use Threads is fascinating.
@johnvoorhees John Voorhees on x
Meta Muse Spark Open weights have been released and it's been tuned through a collaboration with Apple and the MLX team to work great on the M5 Ultra Mac Studio. More on @macstoriesnet: https://www.macstories.net/... [image]
r/apple r on reddit
Apple and Meta team up to make Muse AI model run on Mac computers
@andymstone Andy Stone on x
Meta + Apple + the most capable US open-weight model to date
@parkerortolani Parker Ortolani on x
innovation runs free when you're not fighting, truly a new Apple (and a new Meta) https://www.axios.com/...
@meghanbobrowsky Meghan Bobrowsky on x
Meta today released a new open-weight AI model that can run locally on Apple's high-end Mac computers. It's a big deal that the two companies are collabing after their long feud, during which Mark Zuckerberg in 2018 said he wanted to “inflict pain” on Apple. (1/2)
@alexandr_wang Alexandr Wang on x
great doing business with you john apple 🍎🤝
@meghanbobrowsky Meghan Bobrowsky on x
It's also a mutually beneficial deal. Meta gets more researchers and developers to use its AI model and Apple gets to sell more Macs. Read more here in my story with @RolfeWinkler: https://www.wsj.com/... (2/2)
Lomit Patel Lomit Patel on linkedin
Apple and Meta putting years of rivalry aside to bring powerful AI models to Mac hardware says something important about where this market is heading. …
Jonathan Vanian Jonathan Vanian on linkedin
Apple and Meta team up to make Muse AI open-weight model run on Mac computers - with Kif Leswing — The iPhone maker and social media giant …
@artisny @artisny on bluesky
(*Just* when you think this company could not *possibly* do or say anything that would be even *more* weird or disturbing...) — Lol—Wut ??!! Have they still not read the memo: “Be Normal.” ? — 😱😂 [embedded post]
@0interestrates Rahul on x
this is a pretty big deal if you know about mark's previous relationship with apple [embedded post]
r/SillyTavernAI r on reddit
Meta releases Muse Spark Open. Another open weights model and a pretty strong one too. Not for anyone without a datacenter at home though, but news for the subreddit regardless.
r/actutech r on reddit
Meta a créé un immense modèle d'IA open-weight pour Mac, mais il vous faudra 1 To de RAM pour le faire fonctionner.
Minseok Lee Minseok Lee on linkedin
Big Congrats to AI at Meta on releasing Muse Spark Open in both BF16 and NVFP4! — Kudos also to all NVIDIANs who helped its performance on #NVIDIA #GB300 GPUs …
Tarek Abouzeid Tarek Abouzeid on linkedin
Extremely good news today from Meta announcing Muse Spark Open! With 816B total parameters, 42B active parameters and a 1M-token context window. …
@criccomini Chris on x
> Meta worked with Apple to make the model run locally across two or four connected Mac Studios powered by Apple's M5 Ultra chips, using Apple's MLX framework. Apple comin' for NVidia. Now do it for not $20k... https://www.axios.com/...
@alexandr_wang Alexandr Wang on x
1/ muse spark open is the most capable US open-weight model to date. 816B total params, 42B active. 1M-token context. natively multimodal. built for coding and agentic work like long-horizon tasks, hard software engineering, multi-step reasoning. america! 🇺🇲
@jack_w_rae Jack Rae on x
As promised, Muse Spark is being open sourced today. This was our first base model we trained under the new MSL org, this open weight version has gone through a lot of careful additional training for open-weight release. It's an efficient and capable model, try it out! [embedded …
@eliebakouch Elie on x
here is an overview of the architecture of all the major american open weight models lots of similarities …
@petergostev Peter Gostev on x
This is how Muse Spark Open compares to other Muse releases [image] [embedded post]
@beffjezos @beffjezos on x
American Open Source is so back 🇺🇸🇺🇸 [embedded post]
@ypatil125 Yash Patil on x
Looks like Western Open Weights has a new leader! Incredible work by @alexandr_wang and team! Will be available for training and inference soon on Applied Compute. [embedded post]
@jeremiahdillon Jeremiah Dillon on x
So, Gemma5 has to come before I/O, right? Your move @Google . 😅
@realtjdunham Tj Dunham on x
Meta just made my argument for me. Its new open model, Muse Spark Open, promises “the freedom to run advanced models wherever, including at home.” The setup: two M5 Ultra Mac Studios. The idea won. The next fight is the computer you already own. https://research.meta.ai/...

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