Snorkel AI Raises $350M at $3.5B Valuation as AI Training Data Demand Surges

Data startup Snorkel AI has raised $350 million in fresh funding at a $3.5 billion valuation, CEO Alex Ratner told Reuters on Sept. 22, 2026, as demand from frontier AI labs for complex training data and simulated environments drives rapid growth. The round, led by Insight Partners and S32, with participation from Addition, Greylock and Wells Fargo, values the San Francisco-based company at nearly triple its $1.3 billion valuation from a $100 million raise in May 2025. Snorkel said its annualized revenue run-rate has crossed $350 million, up from roughly $20 million a year earlier, driven by its data-as-a-service business launched in September 2025. Founded in 2019 out of Stanford's AI lab, the company has shifted from software sales to supplying finished datasets and reinforcement-learning environments, pairing human experts with thousands of specialized AI models. It expects to reach profitability this year.