OpenAI has announced that ChatGPT is now free for everyone, opening its latest AI model, Luna, to free users without usage limits. Luna is a lightweight version of the newest model, GPT-5.6, and is described as the fastest and most cost-effective model among those that make up GPT-5.6. Free users can set Luna as their default model for text conversations, with no limits on the number of chats. However, this unlimited access applies only to text conversations; other features, such as file uploads and image generation, remain subject to separate usage limits.