OpenAI Switches GPT-5.5 Instant as ChatGPT's Default Model

On May 5, OpenAI announced that it has made GPT-5.5 Instant the default model for ChatGPT, reducing hallucination rates by 52.5% compared to the previous GPT-5.3 Instant in high-risk domains such as healthcare, legal, and finance, and decreasing inaccurate responses to user-reported factual errors by 37.3%. The model will also be released simultaneously on the API, with reduced emoji abuse.