OpenAI has launched limited access to its GPT-5.6 models, with plans for public availability soon following U.S. government requests.
OpenAI has introduced limited access to its latest GPT-5.6 models—Sol, Terra, and Luna—through API and Codex for a select group of trusted partners, following requests from U.S. authorities.
The initial preview is designed to showcase the models' capabilities to the U.S. government, with plans to make them publicly available in the coming weeks. OpenAI clarified that this arrangement is not intended to be a long-term standard.
Among the models, Sol is positioned as the flagship, Terra as the versatile workhorse, and Luna as the economical choice. Notably, Terra offers performance on par with GPT-5.5 at half the cost, while Luna is highlighted as the most budget-friendly option in the series.
OpenAI claims that GPT-5.6 Sol is its most advanced model yet, featuring a max reasoning mode for detailed task processing and an ultra mode that utilizes sub-agents to accelerate complex assignments. In recent benchmarks, Sol reportedly set a new record in Terminal-Bench 2.1 for command-line tasks and outperformed GPT-5.5 in GeneBench v1 using fewer tokens.
In cybersecurity assessments, all three models demonstrated improved outcomes as the depth of reasoning increased. OpenAI asserts that their security measures for GPT-5.6 are robust, with Sol remaining below the Cyber Critical threshold in the Preparedness Framework and unable to autonomously create fully functional exploits in tests with web browsers.
To ensure security, OpenAI employed over 700,000 GPU hours for extensive testing aimed at identifying vulnerabilities. During this preview phase, additional verification processes may lead to some requests being blocked or delayed.
The new naming convention signifies the model generation, with Sol, Terra, and Luna indicating varying levels of capability. Pricing for the models is structured at $5 for input and $30 for output for Sol, while Terra costs $2.50 and $15, and Luna is priced at $1 and $6, respectively.
OpenAI plans to enhance accessibility for GPT-5.6 Sol on Cerebras starting in July, achieving speeds of up to 750 tokens per second, with access still limited to select clients as the company expands its offerings.
Additionally, it was noted that OpenAI confidentially filed an S-1 form with the U.S. Securities and Exchange Commission in early June as part of preparations for a potential initial public offering.
