Snorkel AI, a company that helps AI labs and businesses build training datasets and simulated environments, has raised $350 million in Series E funding at a $3.5 billion valuation.

The round was led by Insight Partners and S32, with participation from existing investors including Addition, Lightspeed, Greylock, GV and Wells Fargo.

The new funding values Snorkel AI at nearly three times its $1.3 billion valuation from its previous $100 million funding round in May 2025.

Founded in 2019 by Alex Ratner and researchers from Stanford’s AI lab, Snorkel AI initially focused on software for automating data labeling. The company has since expanded into a data-as-a-service model, providing completed training datasets and reinforcement-learning environments to AI developers.

Snorkel uses a combination of software, AI models and human experts to create and review training data. Its platform brings together thousands of specialized AI models and agents with a network of experts working across areas such as coding, law and medicine.

The company said its annualized revenue run rate has grown to more than $350 million, up from around $20 million a year earlier. Snorkel said the growth has been driven largely by increasing demand for its data-as-a-service business, launched in 2025.

The company works with AI labs, cloud providers, enterprises and the US federal government. Coding data is among its largest areas of demand as AI developers increasingly require more specialized data to train and evaluate advanced models.

Snorkel plans to use the new capital to continue expanding its platform and meet growing demand for high-quality training data and simulated environments. The company also expects to reach profitability this year.