Improving GPT‑5.6 Sol in ChatGPT—and expanding access to GPT-5.6 Luna for free users

OpenAI is widening the gap between ChatGPT's everyday and higher-capability model options. The company says GPT-5.6 Sol has been updated for better accuracy and consistency, changes that could make it more dependable for coding, analysis, and repeatable workflows. OpenAI has not provided benchmark results or detailed evaluations in the announcement summary, so builders should validate the model against their own tasks before changing production processes. GPT-5.6 Luna is also becoming more accessible to free ChatGPT users, with unlimited everyday chats. That gives developers and teams a lower-friction way to test routine prompts and lightweight use cases, while Sol appears positioned for work where response quality matters more. Availability is through ChatGPT; no API pricing, rate limits, context-window details, or rollout schedule were specified.