Micro1 raises over $100M at a $4B valuation, Forbes reports

Micro1, a San Francisco-based startup that supplies human-created training data to AI labs, has raised a new funding round of more than $100 million at a valuation of $4 billion. Forbes reported the deal on September 22, citing two people familiar with it. Micro1 declined to comment, so the round has not been officially confirmed by the company.

Eightfold jump in a year

The new valuation is eight times higher than a year ago, when Micro1 was valued at $500 million in September 2025. According to the people cited by Forbes, several of the company's own customers are joining the round, including two frontier AI labs and two cofounders of xAI. Among Micro1's customers the report lists frontier AI labs, Microsoft, Amazon and robotics companies such as 1X.

From recruiting business to data supplier

At the start of 2025, Micro1 was an AI recruiting business generating roughly $7 million in annual revenue. The turn began when a data-labeling company asked it to help recruit hundreds of engineers. Founder Ali Ansari concluded that the larger opportunity was not finding technical workers but supplying labs with high-quality, human-created data to train and evaluate their models. The company repositioned around finding people who can produce that data, using its own AI interviewer to vet engineers, doctors, lawyers and other domain experts. By December 2025, eight months into the pivot, Micro1 had crossed $100 million in annualized revenue. It now generates over $500 million, and in August TechCrunch reported that the company had reached a $500 million gross annual run rate.

Reinforcement learning gyms and a hot market

Beyond expert data, Micro1 has recently moved into "reinforcement learning gyms" — simulated environments built with real-world enterprise data where AI agents practice navigating workplaces. Slack and email threads from companies that have gone out of business are particularly useful for building them. The raise lands in a busy stretch for the sector: on the same day, TechCrunch reported that Snorkel AI had raised a $350 million Series E at a $3.5 billion valuation, nearly triple what it was worth 17 months earlier.