OpenAI Retires Older ChatGPT Models, Focusing on Advanced GPT-5.5 Series

In a strategic move to optimize its offerings and concentrate on its latest innovations, OpenAI has announced the retirement of several older models from the ChatGPT platform. The models being phased out are GPT-4.5 and OpenAI o3. This decision allows the company to dedicate more resources and development efforts to its cutting-edge GPT-5.5 series, which includes models like GPT-5.5 Instant, GPT-5.5 Thinking, and GPT-5.5 Pro. The retirement schedule provides a transition period for users. GPT-4.5 will undergo a 30-day sunset period, becoming officially deprecated from ChatGPT on June 27, 2026. Similarly, OpenAI o3 will have a longer 90-day transition, with its retirement set for August 26, 2026. During these periods, paid ChatGPT users can still manually select and utilize these older models. It's important to note that these changes are specific to the ChatGPT web and mobile applications; developers accessing these models via OpenAI's API services will not be affected by this deprecation. The announcement was made on May 29, 2026, detailing the May 28, 2026, retirement plans.