OpenAI has announced that free and Go tier ChatGPT users will soon receive unlimited text chats with no automatic switching to lesser models. This update includes a transition to GPT-5.6 Luna as the default model, replacing the older GPT-5.5 Instant. While text chats become unlimited, limits on file uploads and image generation will remain.

Free and Go users will also gain access to a new 'Think' button, allowing users to select how much computational thought the AI applies to its responses. For Plus and Pro subscribers, the flagship GPT-5.6 Sol model is being improved to provide more direct responses, tighter formatting, and fewer errors in critical areas like financial or medical prompts.

Internal evaluations show that the new GPT-5.6 Sol model reduced factual errors by approximately 68% compared to its predecessor. While the Chat experience receives these optimizations for everyday use, the versions powering ChatGPT Work and Codex will remain unchanged for now.