OpenAI has announced the launch of its latest GPT-5.1 model that is supposed to make ChatGPT faster and more interactive in conversation, with improvements in intelligence, natural response, and the ability to customize the tone of speech.

The company explained that the update includes two new versions of the model, GPT-5.1 Instant and GPT-5.1 Thinking, and will be available to all ChatGPT users, both subscribers and free plan holders.

The Instant version is the most commonly used default model, as the company described it as warmer, smarter, and better at executing instructions, while the Thinking version focuses on logical thinking abilities, responding faster to simple tasks, and more stable in complex tasks.

The company explained that both models give users the ability to control ChatGPT's tone, to adjust the style of responses according to the nature of the conversation.

The company confirmed that it will soon update the GPT-5 Pro version to the new version 5.1, noting that the 5.1 figure reflects improvements in the base model that was trained on the same structure and data as the GPT-5 model series.

The company said that the most notable difference between GPT-5 and GPT-5.1 is that the latter has a more natural and interactive tone. In another post, she added: "Through early testing, users are often surprised by the kindness and wit of the model while maintaining its accuracy and usefulness.

The Instant model takes advantage of adaptive thinking to determine how much analysis is required to answer, especially in complex questions, and improves its performance in executing instructions, responding quickly without compromising the accuracy of the answer.

In contrast, GPT-5.1 Thinking is able to determine how much analytical power it needs to deal with a question. It adapts the level of thinking to the nature of the query, making it faster in simple answers and more in-depth in long tasks.