OpenAI is releasing GPT-5.1 today, an update to the flagship model it released in August. OpenAI calls it an “upgrade” to GPT-5 that “makes ChatGPT smarter and more enjoyable to talk to.”

The new models include GPT-5.1 Instant and GPT-5.1 Thinking. The former is “warmer, more intelligent, and better at following your instructions” than its predecessor, per an OpenAI release, and the latter is “now easier to understand and faster on simple tasks, and more persistent on complex ones.” Queries will, in most cases, be auto-matched to the models that may best be able to answer them. The two new models will start rolling out to ChatGPT users this week, and the old GPT-5 models will be available for three months in ChatGPT’s legacy models dropdown menu before they disappear.

As part of the update, OpenAI also said it would expand its personality presets for the conversational tone of the models. The total list of options now includes Default, Professional, Friendly, Candid, Quirky, Efficient, Nerdy, and Cynical, per the company’s blog post. OpenAI also said in a release that it would also debut an “experiment for new ways to fine-tune ChatGPT’s style directly from settings,” which some users will begin to be able to access this week.

“With more than 800 million people using ChatGPT, we’re well past the point of one-size-fits-all,” Fidji Simo, the company’s CEO of Applications, wrote in a Wednesday Substack post.

While OpenAI CEO Sam Altman hyped up the announce of GPT-5 in August, the release failed the hype test. Many ChatGPT users were left unimpressed, particularly at the incremental improvements, and expressed frustration over OpenAI’s choice to make it the default model for ChatGPT. There was so much pressure that OpenAI decided it would bring back GPT-4o as an option, a day after the launch of GPT-5.

Microsoft, OpenAI’s strategic AI partner, has also increasingly been looking at rival models from Anthropic after GPT-5 failed to raise the bar enough. Anthropic’s models are now helping power Copilot Researcher, GitHub Copilot, Copilot Studio, and a new Office Agent that is able to produce Word and PowerPoint documents from Microsoft’s own Copilot chat interface.

The announcement of GPT-5.1 comes just weeks after OpenAI launched its AI-powered web browser, ChatGPT Atlas. It has an “agent mode” that’s currently only available to ChatGPT Plus and Pro users, and it works much like the company’s Operator tool to take actions in the browser on behalf of users.