Noam Shazeer, who co-authored a seminal paper that helped catalyze the AI boom, announced his departure in an X post. His move marks a big win for OpenAI, which is vying with Anthropic PBC to develop ever-more sophisticated models ahead of an initial public offering.

OpenAI Chief Research Officer Mark Chen said Shazeer would be the company’s lead for AI architecture research — essentially, studying how to build models. Shazeer said in his post on the social network that he was looking forward to “working with the exceptional team” there.

Shazeer’s departure comes at a pivotal juncture for Google, which is competing with OpenAI, Anthropic and Elon Musk’s SpaceX in a critical industry.

Google’s stock has soared in recent months, riding enthusiasm for the company’s broad role in developing AI models, the chips to power them, and consumer apps that reach billions of people. Yet Google has fallen behind in the market to sell AI coding tools to businesses. Former employees have said the company’s own researchers must navigate internal politics to access computing power.

Shazeer co-authored “Attention Is All You Need,” a 2017 research paper from Google that described the transformers that underpin generative AI today. He began work at the US company in 2000, making key contributions to the search engine’s spelling corrector and ad technology, according to his personal website.

He left in 2021 to found Character.AI, a chatbot startup, after Google proved slow to release products incorporating generative AI. After rejoining in 2024 as part of a licensing deal that valued his firm at $2.5 billion, Shazeer co-led development of the company’s flagship Gemini AI model.

“We are grateful for Noam’s meaningful contributions to Google over the years and we wish him well,” a Google spokesperson wrote in an email.