[DigitalToday reporter Chi-gyu Hwang (황치규)] OpenAI is introducing unlimited text chat for ChatGPT free users and paid users. TechCrunch reported on Aug. 6 (local time) that ChatGPT, which recently surpassed 1 billion weekly users, is also switching the default model for free and paid users from GPT-5.5 to GPT-5.6 Luna.

A Think button, which applies higher reasoning performance to complex questions, will also be added for free users and paid users. Separate limits will remain for files, images, audio and image generation.

The timing will differ. Other updates, including the model change for free users and paid users, will take effect from this week, while unlimited text chat and the Think button will be provided next week.

Plus and Pro users are also subject to changes. They will be able to use GPT-5.6 Sol, which has been improved to be better suited for fast tasks such as answering questions, web research, advice, planning, writing and decision-making. The Sol model is designed to provide more concise and robust answers.

This GPT-5.6 Sol is a separate version from the GPT-5.6 Sol used for Codex and Work. The models for Codex and Work will remain unchanged.

A "reasoning slider" will also be added for Plus and Pro users to adjust how much reasoning is applied to answers. Users can adjust the level of reasoning depending on the complexity of the question and the steps required to solve it.