Overview

• GPT-5 is now available to all ChatGPT users and API developers, replacing previous default models during a 60-day transition period.
• A built-in routing mechanism directs straightforward requests to lightweight variants and allocates test-time compute for complex reasoning tasks automatically.
• Developers can choose from three API options—full GPT-5, GPT-5 Mini and GPT-5 Nano—to balance performance, latency and cost.
• OpenAI has introduced safe completions and other safety layers to reduce hallucinations by up to 80 percent in reasoning mode.
• Early user feedback has prompted refinements to the real-time router and rate limits to smooth the rollout and improve reliability.