OpenAI is making its newest flagship model free for everyone: GPT-5.6 Luna becomes the default model for ChatGPT Free and Go users this week, with unlimited text chats rolling out next week alongside a new 'Think' button for higher-reasoning answers. The company says the changes are designed to give everyone access to its frontier models without a subscription.
In an announcement also covering improvements to GPT-5.6 Sol, OpenAI said its internal evals put Luna's factual-error rate 62% below GPT-5.5-Instant, and Sol's 68% below the same baseline. The unlimited text chats replace the previous daily caps for free-tier users; file, image, voice and image-generation limits remain in place.
The new Think button lets users explicitly request a model to spend more compute on harder problems — reasoning step by step before answering — a capability previously gated behind paid tiers. The Verge noted the change makes ChatGPT's default AI model the recently released GPT-5.6 Luna, while TechCrunch framed it as part of OpenAI's broader push to defend its consumer base as rivals race to offer free frontier models.
The rollout comes amid intensifying competition in consumer AI, with major labs shipping free tiers and aggressively priced models. Making the flagship free is OpenAI's latest bid to keep ChatGPT the default place people go for AI.
