OpenAI Releases GPT-5.6 Luna and Sol, Expanding Reasoning to Free Users

OpenAI has announced the release of its GPT-5.6 model family, providing Free and Go users with unlimited text chats using GPT-5.6 Luna and access to the reasoning "Think" button. Additionally, Plus and Pro users now have access to the updated GPT-5.6 Sol model, which includes a slider to adjust reasoning effort. This update democratizes advanced AI reasoning capabilities by bringing them to non-paying users, while significantly reducing factual errors in high-stakes domains like finance, medicine, and law for premium users. The GPT-5.6 Sol model produced 68% fewer factual errors compared to GPT-5.5 Instant, and the new slider allows Plus and Pro users to control the depth of reasoning effort per response. GPT-5.6 Luna serves as a highly cost-effective, near-frontier model variant.