Snorkel AI hits $3.5 billion valuation in Series E

Data-labeling startup Snorkel AI has secured $350 million in a Series E funding round, boosting its valuation to $3.5 billion. Led by Insight Partners and S32, the investment nearly triples the $1.3 billion valuation the seven-year-old company achieved just 17 months ago during a $100 million Series D round. Existing backers, including GV, Wells Fargo, Addition, Lightspeed, and Greylock, also joined the round. This massive valuation spike is supported by an eighteenfold increase in Snorkel's annualized revenue run rate over the past 12 months, which has now reached $375 million.

For AI practitioners, Snorkel's rapid growth reflects a significant shift in how machine learning teams source training data. Originally focused on software for automating data labeling, the company transitioned last year to a "data-as-a-service" model. Instead of acting solely as a marketplace for human annotators, Snorkel now delivers fully completed datasets and reinforcement learning environments. It achieves this through a hybrid methodology that combines its proprietary software and models to generate synthetic data alongside validation from domain-specific human experts.

This pivot addresses the intense demand from AI labs for sophisticated training inputs. Other players in the AI data space are experiencing similar surges; Mercor has reached $2 billion in gross annualized revenue, Handshake has hit $1 billion, and Micro1 has scaled to $500 million. However, while those competitors typically pay 60% to 70% of their top-line revenue directly to human specialists, Snorkel's model is different. Because it sells complete datasets and simulated environments rather than human labor, its expert payments are categorized under cost of goods sold rather than impacting its headline revenue figures.

Snorkel AI was commercially launched in 2019 by co-founder and CEO Alex Ratner. The startup emerged after four years of academic research conducted by Ratner and his colleagues at a Stanford University AI laboratory.