OpenAI announced today that its flagship AI model has been upgraded to GPT-5.1 and will start pushing this new version to ChatGPT users this week. Compared with GPT-5 released in August this year, this update is officially called by OpenAI as "making ChatGPT smarter and more interesting" and brings many improvements and new features.
GPT-5.1 is divided into two versions: "Instant" and "Thinking". According to the official introduction, the "Instant" model is superior to the previous generation model in terms of temperature, intelligence and command understanding. The "Thinking" model is more efficient and durable in dealing with complex problems, and the response speed on simple tasks has also been improved. The system automatically matches users with models suitable to answer the current question. The original GPT-5 model will still be available in ChatGPT as a "legacy model" for three months, after which it will be taken offline.
Another highlight of this update is that OpenAI has greatly enriched the "personality preset" options for conversation styles. Users can now flexibly switch between "default, professional, friendly, candid, eccentric, efficient, nerdy, and cynical" personalities. OpenAI also announced that it will experiment with allowing some users to fine-tune the language style of ChatGPT directly in the settings.
Fidji Simo, CEO of the OpenAI application department, said in a Substack post on Wednesday: "ChatGPT has more than 800 million users, far beyond what a standard model can handle."
When OpenAI first launched GPT-5 in August this year, the hype and expectations were high, but the actual performance failed to satisfy some users. Many people thought the upgrade was limited and were dissatisfied with GPT-5 becoming the default model for ChatGPT. OpenAI eventually even reopened the GPT-4o option just one day after its release in response to user demand.
In addition, OpenAI's strategic partner Microsoft also began to seek cooperation with other AI companies such as Anthropic after failing to achieve a breakthrough in GPT-5. Related models have been applied to product lines such as Copilot Researcher, GitHub Copilot, Copilot Studio, and Office Agent, which can create Word and PowerPoint documents through the chat interface.
It is worth mentioning that just a few weeks before GPT-5.1 came out, OpenAI had just released the AI-driven web browser ChatGPT Atlas. Currently, the "agent mode" is only open to ChatGPT premium subscribers, which can directly perform operations on behalf of the user in the browser.