Snorkel AI has raised a $350 million Series E at a $3.5 billion valuation, nearly triple the $1.3 billion valuation it received in a $100 million Series D 17 months earlier. Insight Partners and S32 led the round, with Addition, Lightspeed, Greylock, GV and Wells Fargo among participating existing investors. Snorkel's annualized revenue run-rate stands at $375 million, an 18-fold increase over the past 12 months, as AI labs seek specialized training datasets and reinforcement-learning environments. The company has shifted from automated data-labeling software toward Data-as-a-Service, supplying completed datasets through a hybrid model that combines synthetic-data generation with subject-matter experts. Snorkel says expert payments are recorded as cost of goods sold because it sells completed data products rather than human labor. Co-founder and CEO Alex Ratner launched Snorkel commercially in 2019 after four years of research with his team at a Stanford AI lab.