OpenAI made more than 20 major announcements across ChatGPT, Codex, its models, and more at DevDay 2026. It introduced agents that can take on ongoing responsibilities and new ways for people and AI to work together. The company also expanded its commitment to an open ecosystem by opening up ChatGPT as a shared surface where humans and agents can collaborate and where developers can directly launch new native experiences. There is now a new Pro 500 plan that offers 25 times the ChatGPT Plus allowance and includes access to Ultrafast.