OpenAI DevDay 2025 was a high-velocity developer showcase (held in early October 2025) where OpenAI unveiled a broad slate of products, toolkits, SDKs and model releases designed to move the company from model-provider to platform-operator: apps that run inside ChatGPT, a drag-and-drop agent builder (AgentKit), the general-availability rollout of Codex for developer workflows, and a […]