OpenAI releases GPT-5 with a router between fast and reasoning models

OpenAI/GPT models

OpenAI released GPT-5 to all ChatGPT users, featuring a fast model for routine questions, a deeper reasoning model for hard problems, and a real-time router that decides which to use based on request complexity. The router is trained on real signals including user preference and measured correctness, improving over time.

• Three-component system: fast efficient model, reasoning model for deep problems, and smart router.
• Router trained on user signals (switching behavior, preference ratings, correctness measurement); improves over time.
• Pro subscribers get GPT-5 Pro with longer reasoning; cost model separates cheap quick answers from compute-intensive reasoning.
• Replaces earlier approach of separate fast and reasoning models with dynamic routing.