Anthropic hired Andrej Karpathy to turn his viral "autoresearch" experiment into a full team, the company confirmed Tuesday, marking one of the biggest talent acquisitions in the escalating AI wars.
The OpenAI founding member and former Tesla AI director announced his move in a post on X that drew nearly 3 million views in its first hour. "I think the next few years at the frontier of LLMs will be especially formative," Karpathy wrote.
"I am very excited to join the team here and get back to R&D."
Karpathy starts this week on Anthropic's pretraining team, reporting to Nicholas Joseph, another ex-OpenAI researcher who was an early Anthropic employee. His mandate: build a team focused on using Claude to accelerate pretraining research itself, the large-scale training runs that give Claude its core knowledge and capabilities. The role is a direct product of Karpathy's own viral work. In March, he wired up an AI coding agent, handed it a single small language model, and let it run unsupervised for two days, testing and tweaking the training code on its own.
After 700 experiments and 20 self-discovered optimizations, the same tweaks applied to a larger model cut training time by 11%. He called the method autoresearch: "Part code, part sci-fi, and a pinch of psychosis." The technique became known as "the Karpathy Loop."
Karpathy's career has traced the entire arc of modern AI. He co-founded OpenAI in 2015 alongside Sam Altman and Ilya Sutskever, left to lead Tesla's Autopilot computer vision team, returned to OpenAI in 2023, departed again in February 2024, and most recently ran Eureka Labs, an AI education company.
He became a household name in tech circles in February 2025, when he coined "vibe coding", a term for letting AI models write code while the human "fully gives in to the vibes." Collins Dictionary named it Word of the Year. The phrase sparked the "SaaSpocalypse" debate, with tens of billions in stock valuations evaporating as companies raced to build their own AI agents. The model Karpathy used in that original tweet was Anthropic's Claude. The hire lands as Anthropic's momentum accelerates. The company topped CNBC's Disruptor 50 list this year, and its secondary market valuation recently surpassed $1 trillion, overtaking OpenAI.
Anthropic closed a $30 billion funding round in February at a $380 billion valuation.
"Excited to welcome Andrej to the Pretraining team," Joseph wrote on X. "I can't think of anyone better suited to do it."
