OpenAI launched a major upgrade to the GPT-5 series with the launch of GPT-5.1, which aims to improve ChatGPT’s performance and interaction quality. The update includes two new models, GPT-5.1 Instant and GPT-5.1 Thinking. OpenAI defined the Instant model as "warmer, more intelligent, and better at following instructions". The rollout will start with Pro, Plus, Go, and Business plan users.