
GPT-5 family (GPT-5.5 / GPT-5.6)
OpenAI's prior frontier large-language-model family. GPT-5.5 (April 2026) was the broadly available flagship, built for agentic coding, computer use, and knowledge work. GPT-5.6 - variants Sol, Terra and Luna - opened to the public on July 9, 2026 after an initial government-gated preview. GPT-6 Astra, launched September 3, 2026, is now the new flagship (see that product).





