Snorkel AI, a company that assists AI research labs and enterprises in creating training datasets and simulated environments, has secured $350 million in Series E funding at a $3.5 billion valuation. The round was co-led by Insight Partners and S32, and it values the seven-year-old company at nearly three times the $1.3 billion valuation it achieved when it raised $100 million in Series D funding 17 months earlier. Addition, Lightspeed, Greylock, GV, and Wells Fargo were among the existing investors who also joined the round.

Originally, Snorkel offered software for automating data labeling, but last year it pivoted to delivering finished datasets to customers—an offering it describes as data-as-a-service. Instead of functioning solely as a marketplace for human experts, Snorkel takes a hybrid approach, combining its software and models to generate synthetic data with contributions from subject matter experts.

According to Snorkel, its current annualized revenue run-rate has reached $375 million, representing an 18-fold increase over the past 12 months. This surge is driven by AI labs' relentless demand for premium training data. Other data companies that market themselves as AI data labs have experienced similarly explosive growth.

It's worth noting that because these companies typically pay out about 60% to 70% of their top-line income directly to the domain specialists performing the work, their actual net annual revenue is considerably lower than those headline gross figures. Since Snorkel sells reinforcement learning (RL) environments and complete datasets rather than human labor, payments to its human experts are categorized within its cost of goods sold instead of being counted in the headline annualized revenue numbers, the company explained.

Snorkel launched commercially in 2019, following four years of research by co-founder and CEO Alex Ratner and his team at a Stanford AI lab.