OpenAI releases GPT-5.5 Instant, a new default model for ChatGPT

On Monday, OpenAI released a new foundation model called GPT-5.5 Instant, which will replace GPT-5.3 Instant as the default ChatGPT model. The company said the model reduces hallucination in sensitive areas such as law, medicine, and finance, while maintaining the low latency of its predecessor.

OpenAI released the latest GPT-5.5 model last month with the company claiming improvements in areas like coding and knowledge work.