OpenAI launched the o1 model during its Mini Dev Day, enhancing its API with features like function calling, structured outputs, and vision inputs. The model offers improved reasoning and performance, allowing developers to control response quality and speed. Additionally, OpenAI revamped its Realtime API for faster, more affordable AI interactions and introduced preference fine-tuning for better model alignment. New SDKs for Go and Java were also released, expanding developer tools and resources.