OpenAI released GPT-5.6 on July 9, 2026, after initially limiting it to trusted partners on June 26. The public rollout includes three variants: Luna, Terra, and Sol, ranked from least to most capable.

Sol is OpenAI’s “workhorse” and “best coding model yet.” The model excels at complex reasoning, code generation, and agentic workflows. It supports enterprise work, scientific research, cybersecurity, and developer productivity.

Three Tiers

Luna is the lightweight option for basic tasks. Terra sits in the middle, balancing capability with cost. Sol offers maximum performance for demanding applications. This three-tier approach lets users match model capability to their use case and budget.

The models were designed for coding, scientific work, and cybersecurity specifically. OpenAI emphasizes that Sol is its “strongest cybersecurity model yet” for threat modeling, code review, and blue team activities.

Delayed Public Release

Government restrictions from the Trump administration initially forced OpenAI to keep GPT-5.6 private. The company planned a June public launch but had to delay to comply with export control and national security requirements. The July release finally makes the model available to paying customers.

OpenAI also announced GPT-Live, a new voice model generation released around July 8. Voice capabilities let developers build audio interfaces on top of the GPT-5.6 models.

Competitive Positioning

Google and Microsoft released their own model updates in the same period. The market is crowded with capable models at different price points. OpenAI argues Sol offers the best performance and reliability for production workloads.

GPT-5.6 is available now via OpenAI’s API. Developers can choose Luna, Terra, or Sol based on their performance and cost requirements.