#GPT-5.6 Luna

OpenAI is expanding ChatGPT Free and Go access with unlimited text chats, a new Think button, and GPT-5.6 Luna as the default model. GPT-5.6 Luna will replace GPT-5.5 as the default model for Free and Go users starting this week. When selected, ChatGPT will give GPT-5.6 Luna more time to work through harder requests. Plus and Pro subscribers can access an updated GPT-5.6 Sol, along with a slider that controls how much reasoning the model uses for a response. In an internal evaluation, OpenAI said responses containing at least one factual error were 62% less common with Luna and 68% less common with Sol compared with GPT-5.5 Instant. OpenAI has announced the GPT-5.6 series. These are three new AI models called Sol, Terra and Luna. GPT-5.6 Sol is the flagship model and comes with OpenAI's strongest AI safety protections yet according to the brand. Read more in our articles including "OpenAI expands ChatGPT free access with GPT-5.6 Luna" and "OpenAI unveils GPT-5.6 with Sol, Terra, Luna AI models".