OpenAI has announced plans to retire its GPT-4.5 and OpenAI o3 models from the ChatGPT web and mobile interfaces to optimize resource allocation. The decision will allow the company to focus on its latest GPT-5.5 series, which includes GPT-5.5 Instant, GPT-5.5 Thinking, and GPT-5.5 Pro models. The retirement schedule specifies that GPT-4.5 will enter a 30-day transition period, with official deprecation on June 27, 2026. Meanwhile, OpenAI o3 will have a 90-day transition period, with deprecation set for August 26, 2026. Until these dates, paid ChatGPT users can still select these models manually. OpenAI's API services will not be affected, allowing developers continued access to these models via the API.