Andrej Karpathy, a prominent AI researcher who co-founded and previously worked at OpenAI, and before that led artificial intelligence efforts at Tesla, has now joined Anthropic.

“I’ve joined Anthropic,” Karpathy announced on X Tuesday. “I think the next few years at the frontier of LLMs will be especially formative. I am very excited to join the team here and get back to R&D.”

Karpathy began his role at Anthropic this week, focusing on pre-training under team lead Nick Joseph. Pre-training is the process responsible for the large-scale training runs that provide Claude with its core knowledge and capabilities, according to the company. It is also one of the most expensive and compute-intensive stages of building a frontier model.

Karpathy is among a select group of researchers capable of bridging the gap between LLM theory and large-scale training practice. By recruiting him to build such a team, Anthropic is signaling its belief that AI-assisted research—rather than sheer computing power—is the key to staying competitive with OpenAI and Google.

While at OpenAI, Karpathy concentrated on deep learning and computer vision until he left in 2017 to join Tesla. There, he led the Full Self-Driving (FSD) and Autopilot programs before departing in 2022. He then returned to OpenAI for a year, leaving again in 2024 to launch Eureka Labs, a startup focused on applying AI assistants to education.

Karpathy hasn’t shared many updates about Eureka Labs since its launch, and it remains unclear whether the renowned researcher will continue with the startup. He has also taught an online course called *Neural Networks: Zero to Hero*, which helps students learn to build neural networks from scratch using code, and runs a YouTube channel where he semi-regularly posts lectures on LLMs and AI.

“I remain deeply passionate about education and plan to resume my work on it in time,” Karpathy said.

Separately, Anthropic has also brought on Chris Rohlf to its frontier red team, which stress-tests advanced AI models against severe threats. Rohlf is a cybersecurity industry veteran with over 20 years of experience. He previously worked at Yahoo’s highly respected cybersecurity team, known as “The Paranoids,” and more recently at Meta, where he spent six years before joining Anthropic. Rohlf was also a fellow at Georgetown’s Center for Security and Emerging Technology, where he contributed to the CyberAI project.

“We have a real opportunity in front of us to dramatically improve cyber security with AI,” Rohlf said in a post on X. “I can’t think of a better company or team to join at this critical moment in time.”