#1OpenAI Makes GPT-5.5 Instant the Default ChatGPT Model
OpenAI rolled out GPT-5.5 Instant as the new default model for all ChatGPT users on May 5, delivering 52.5% fewer hallucinations on high-stakes prompts in medicine, law, and finance. The model uses 30% fewer words per response and can reference past conversations and Gmail for personalization. Paid users retain GPT-5.3 Instant as a fallback for three months.