OpenAI released GPT-5.5 Instant as the new default model for all ChatGPT users, replacing GPT-5.3 Instant. The company states the update provides smarter and clearer responses.
Internal tests show GPT-5.5 Instant generates answers that are 30% more concise. The model produced 52.5% fewer factual hallucinations on high-stakes topics compared to its predecessor.
Paid subscribers gain enhanced personalization features. ChatGPT can now reference past conversations and connected files to tailor responses.
The move increases competitive pressure on rivals like Google to advance their large language models. The rollout is immediate for all users and available via the API.