GPT-5.6 API

What Is GPT-5.6?

GPT-5.6 is OpenAI's model family, first previewed on June 26, 2026 to a limited group of trusted partners, then released generally on July 9, 2026. It ships in three tiers: Sol (the flagship), Terra (a balanced mid-tier model), and Luna (the most cost-efficient tier). Each tier is also available in a Pro configuration that runs the same underlying model with reasoning mode set to pro for harder tasks.

OpenAI describes GPT-5.6 as bringing stronger capabilities in coding, scientific research, and cybersecurity, calling Sol its "strongest cybersecurity model yet." The company reported Sol is roughly 54% more token-efficient on AI coding tasks compared to GPT-5.5.

The Three Tiers

Sol
OpenAI's flagship GPT-5.6 model, built for the deepest reasoning on software engineering, research, and agentic work.

Terra
A balanced tier for everyday coding and agentic work at roughly half the cost of Sol.

Luna
The fastest and most cost-efficient tier, built for high-volume, latency-sensitive workloads.

Explore the GPT-5.6 Models

Each tier and its Pro configuration has its own API page with full pricing, technical specs, and code samples: GPT-5.6 Sol, GPT-5.6 Sol Pro, GPT-5.6 Terra, GPT-5.6 Terra Pro, GPT-5.6 Luna, and GPT-5.6 Luna Pro.

Sources: https://openai.com/index/gpt-5-6/ · https://openai.com/index/previewing-gpt-5-6-sol/ · https://en.wikipedia.org/wiki/GPT-5.6

GPT-5.6 is documented as suitable for programming, knowledge work, cybersecurity, and science.

It is also documented for defensive cybersecurity tasks, including secure code review, patching, threat modeling, and blue teaming.

OpenAI also describes it as useful for complex work across coding, knowledge work, research, cybersecurity, science, computer use, and design.

For builders, it is presented as a strong fit for high-volume workloads, latency-sensitive interactions, and repeated steps within agentic workflows.