GPT-5.6 Sol

GPT-5.6 Sol

OpenAI
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About

GPT-5.6 Sol is a next-generation OpenAI model designed for advanced reasoning, coding, agentic workflows, biology analysis, cybersecurity support, and complex knowledge work. It is part of the GPT-5.6 model family alongside Terra and Luna, with Sol positioned as the flagship model for the most demanding tasks. The model introduces a new max reasoning effort for deeper thinking and an ultra mode that uses subagents to accelerate complex work beyond a single-agent approach. GPT-5.6 Sol shows strong performance in command-line coding workflows, long-horizon security tasks, genomics analysis, vulnerability research, debugging, patch development, and defensive testing. OpenAI pairs the model’s stronger capabilities with layered safeguards, real-time misuse classifiers, account-level review, automated red-teaming, and enterprise controls for sensitive workflows. GPT-5.6 Sol helps developers, enterprises, researchers, and security teams complete sophisticated technical work.

About

Muse Spark Open is an open-weight, natively multimodal language model for developers and organizations building AI applications, coding systems, and agentic workflows. The released model has 816 billion total parameters, 42 billion active parameters, and a 1-million-token context window. Teams can download the model weights, run inference through supported engines such as vLLM, SGLang, TensorRT-LLM, Hugging Face Transformers, Apple MLX, llama.cpp, or Unsloth, and customize the model using PyTorch. It supports long-context reasoning, software engineering, coding, tool use, and multimodal inputs. Deployment options include cloud inference through listed API providers or self-hosting on compatible GPU systems; Meta documents a desktop setup using two Apple M5 Ultra Mac Studio computers. The model is released under the Muse Model License with limited commercial terms.

Platforms Supported

Windows Not Supported
Mac Not Supported
Linux Not Supported
Cloud Supported
On-Premises Not Supported
iPhone Not Supported
iPad Not Supported
Android Not Supported
Chromebook Not Supported

Platforms Supported

Windows Supported
Mac Supported
Linux Supported
Cloud Supported
On-Premises Supported
iPhone Not Supported
iPad Not Supported
Android Not Supported
Chromebook Not Supported

Audience

GPT-5.6 Sol is best suited for developers, enterprise teams, AI engineers, researchers, security teams, cyber defenders, software organizations, biotechnology teams, and advanced technical users that need frontier reasoning, coding support, agentic workflows, biology analysis, defensive cybersecurity assistance, API access, Codex integration, and stronger safety controls

Audience

AI developers, machine learning engineers, software engineers, AI researchers, enterprise development teams, and organizations seeking customizable open-weight multimodal models for local inference, autonomous agents, complex coding, and long-context AI applications

Support

Phone Support Not Supported
24/7 Live Support Not Supported
Online Supported

Support

Phone Support Not Supported
24/7 Live Support Not Supported
Online Not Supported

API

Offers API Supported

API

Offers API Not Supported

Screenshots and Videos

Screenshots and Videos

Pricing

$4 per 1M tokens (input)
$4 input / $20 output per 1M tokens
Free Version Not Supported
Free Trial Not Supported

Pricing

$0
Model weights are available at no charge under the Muse Model License, which has limited commercial-use terms. Hosted inference providers set their own usage prices.
Free Version Supported
Free Trial Not Supported

Reviews/Ratings

Overall 5.0 / 5
ease 5.0 / 5
features 5.0 / 5
design 5.0 / 5
support 5.0 / 5

Reviews/Ratings

Overall 5.0 / 5
ease 5.0 / 5

Pros & Cons from Real Users

Pros

  • GPT-5.6 Sol feels like the model I would reach for when the task is actually hard. As a developer, I like that it is built for deeper reasoning, coding, long-horizon planning, and agentic workflows instead of just quick prompt-and-response work. It is especially appealing for complex debugging, multi-step code changes, research-heavy engineering tasks, and agents that need to coordinate tools without losing the plot. The fact that OpenAI is positioning Sol as the most capable model in the GPT-5.6 family makes sense, because this is the one I would want for serious engineering work.

Cons

  • The main downside is that Sol is the premium option, so I would not use it for every single task. OpenAI lists Sol at a higher token price than Terra or Luna, which means developers will still need to be smart about routing simple jobs to cheaper models.

Pros & Cons from Real Users

Pros

  • Meta finally opened up a genuinely frontier-level Muse model. The 1M-token context window and 42B active parameters make it strong enough for large repos, long agent sessions, multimodal work, and complex coding without feeling like a stripped-down open model. The local deployment story is also a huge deal. Being able to run something this capable on two M5 Ultra Mac Studios is impressive, especially for teams that want more control over data, infrastructure, and customization. I also like how much of the stack is open around it. Muse Spark Open works with MLX, vLLM, SGLang, TensorRT-LLM, Transformers, llama.cpp, and Unsloth, and Meta is making the weights available through Hugging Face, SageMaker, Google Cloud Model Garden, and Microsoft Foundry.

Cons

  • Even though it is technically desktop-capable, needing two M5 Ultra Mac Studios for the full local experience is still a serious setup, so most developers will probably use hosted inference instead.

Training

Documentation Supported
Webinars Not Supported
Live Online Not Supported
In Person Not Supported

Training

Documentation Supported
Webinars Not Supported
Live Online Not Supported
In Person Not Supported

Company Information

OpenAI
Founded: 2015
United States
openai.com

Company Information

Meta
Founded: 2004
United States
research.meta.ai/blog/muse-spark-open

Alternatives

Alternatives

Laguna XS 2.1

Laguna XS 2.1

Poolside

Categories

AI Coding Models Supported
AI Models Supported
AI Vision Models Supported

Categories

AI Coding Models Supported
AI Models Supported
AI Receptionists Supported
Foundation Models Supported
Multimodal Models Supported

Integrations

OpenRouter Supported
Amazon Web Services (AWS) Supported
Anuma Supported
App0 Supported
ChatGPT Atlas Supported
ChatGPT Plus Supported
Fireworks AI Not Supported
Flowise Supported
GPT-5.1-Codex Supported
GPT-5.5 Thinking Supported
Lorka Supported
Microsoft SharePoint Supported
Muse Supported
NextDocs Supported
Novelcrafter Supported
OpenClaw Supported
OpenCode Supported
Solidity Supported
Together AI Not Supported
vLLM Not Supported

Integrations

OpenRouter Supported
Amazon Web Services (AWS) Not Supported
Anuma Not Supported
App0 Not Supported
ChatGPT Atlas Not Supported
ChatGPT Plus Not Supported
Fireworks AI Supported
Flowise Not Supported
GPT-5.1-Codex Not Supported
GPT-5.5 Thinking Not Supported
Lorka Not Supported
Microsoft SharePoint Not Supported
Muse Not Supported
NextDocs Not Supported
Novelcrafter Not Supported
OpenClaw Not Supported
OpenCode Not Supported
Solidity Not Supported
Together AI Supported
vLLM Supported
Claim GPT-5.6 Sol and update features and information
Claim GPT-5.6 Sol and update features and information
Claim Muse Spark Open and update features and information
Claim Muse Spark Open and update features and information