"This is an AI-powered web browser built around ChatGPT," OpenAI chief Sam Altman said in a streamed presentation.

OpenAI has ramped up its challenge to Google, which has responded by rapidly building more AI capabilities into search and across its platform.

Altman and a team of executives demonstrated an "agent" mode that has a chatbot conduct searches on a user's behalf.

Altman said that in agent mode, ChatGPT uses the web browser independently, returning with what it finds.

"It's got all your stuff and is clicking around," Altman said.

"You can watch it or not, you don't have to, but it's using the internet for you."

Atlas will go live Tuesday on computers powered by Apple's operating system free of charge, but agent mode will only be available to users of paid Plus or Pro versions of ChatGPT, according to Altman.

"We want to bring this to Windows and to mobile devices as quickly as we can," Altman said, without providing a timeline.

"This is still early days for this project."

Some Atlas offerings demonstrated in the stream seemed similar to features already incorporated into Google Chrome and Microsoft Edge internet search browsers.

- Pressure on Google -

Tech industry rivals Amazon, Google, Meta, Microsoft and Elon Musk's xAI have been pouring billions of dollars into artificial intelligence since the blockbuster launch of the first version of ChatGPT in late 2022.

"OpenAI's browser puts pressure on Google," Emarketer technology analyst Jacob Bourne told AFP.

"This is another step in the AI race as tech companies try to make their AI interfaces the first point of contact for internet users."

OpenAI has an opportunity to ride the popularity of ChatGPT to win people over to its browser, according to the analyst.

However, Bourne noted that Google has a significant infrastructure advantage in terms of providing browser capabilities to billions of users.

A big question is how well Atlas will perform when under pressure from the kinds of user volume handled by Google, he added.

The debut of Atlas comes on the heels of Google escaping a breakup of its Chrome browser in a major US competition case, but with the judge imposing remedies whose impact remains uncertain just as AI starts to compete with search engines.

Judge Amit Mehta, who found a year ago that Google illegally maintained monopolies in online search, did not order the company to sell off its widely-used Chrome browser.

Instead, he ordered remedies including requirements to share data with other firms so they could develop their own search products, and barring exclusive deals to make Google the only search engine on a device or service.

Mehta himself noted that the landscape has changed since the US Justice Department and 11 states launched their antitrust case against Google in 2020.

- Challenges -

OpenAI, Perplexity, and Microsoft have been ramping up challenges to Google, which dominates the online search market where it earns most of its revenue through targeted advertising.

OpenAI recently unveiled a new feature for ChatGPT, the leading generative AI model with 800 million weekly users, enabling it to interact with everyday apps like Spotify and Booking.com.

The new functionality enables ChatGPT to interact with various apps to select music, search for real estate or explore hotel and flight booking sites.

Meanwhile, Perplexity AI in August announced a new model for sharing search revenue with publishers.

The company's media partners will get paid when their work is used by Perplexity's Comet browser or AI assistant to satisfy queries or requests, according to the San Francisco-based startup.

Perplexity is one of Silicon Valley's hottest startups, whose AI-powered search engine is often mentioned as a potential disruptor to Google.

Google shares were down slightly more than one percent in trading that followed OpenAI announcing Atlas.