Snorkel AI, a San Francisco-based company developing advanced data infrastructure for artificial intelligence, has raised $350 million at a $3.5 billion valuation in a financing round co-led by Insight Partners and S32. Existing investor Addition also participated significantly. The funding will support the expansion of Snorkel’s agentic data factory, which supplies the specialized datasets, environments, and evaluation frameworks used to train and assess increasingly sophisticated AI systems.
New investors in the round include March Capital, Blumberg Capital, Allegis Capital, Frontline, Standard, and Third Point Ventures.
Existing investors Greylock, Lightspeed, GV, Factory, Prosperity7, Walden Catalyst, and Wells Fargo also participated.
Snorkel plans to use the financing to increase its capacity to serve leading AI laboratories and enterprises while extending its research and technology into additional industries, AI modalities, and applications.
Founded in 2019 out of the Stanford AI Lab, Snorkel develops tools and services for building the specialized data required to improve advanced AI systems.
The company is expanding beyond conventional data labeling, which typically involves assigning categories or other relatively simple annotations to existing information.
Its newer offerings focus on what Snorkel describes as Data 2.0, an approach designed for advanced and agentic AI models that must complete complex, multistep tasks.
These systems require sophisticated training and evaluation materials, including realistic task environments, expert-developed instructions, and detailed assessment criteria.
Creating such materials can take highly qualified specialists hours or days, particularly in industries where accurate outcomes depend on substantial professional knowledge.
Snorkel’s agentic data factory combines expert human involvement with proprietary technology to produce these research-grade datasets and evaluation environments at greater scale.
The company works with leading AI laboratories and enterprises on data used for frontier model training, evaluation, and performance measurement.
Its expert Data-as-a-Service offering, launched in September 2025, addresses the growing demand for specialized data development among organizations building advanced AI systems.
Snorkel intends to expand this business into additional high-value sectors, including healthcare, law, and software engineering.
These industries require AI systems to perform complex tasks involving specialized knowledge, detailed reasoning, and accurate responses to information that may evolve throughout a workflow.
The new funding will also support development of Snorkel’s core research capabilities and enable the company to expand into additional types of data and model architectures.
Snorkel’s founding team has made extensive contributions to data-centric artificial intelligence. According to the company, its research includes more than 250 peer-reviewed papers with over 25,000 citations.
The company plans to continue supporting open research through initiatives such as its Open Benchmarks Grants program, which encourages the development of publicly available AI evaluation resources.
The financing provides additional resources as Snorkel expands its role in the development of training and evaluation infrastructure for frontier and enterprise AI.
KEY QUOTES:
“The teams pushing the frontier want a research data partner who pioneers the science of data development. That’s what Snorkel was built to be: the frontier lab for agentic data, combining human excellence with over a decade of research and technology.”
Alex Ratner, Co-Founder and CEO of Snorkel AI
“Snorkel’s research-grade approach to AI data, environments, and measurement is becoming an increasingly important ingredient in building capable and reliable AI systems – and their demonstrated growth at scale reflects that. We’re excited to back Alex and the team as they continue to bring their frontier AI data factory capabilities to longer-running, complex work in high value industries like healthcare, law, and software engineering.”
Lonne Jaffe, Managing Director at Insight Partners
“Snorkel’s expert-agentic environments create a unique flywheel between human expertise and AI, delivering data at the speed and quality that enables a new era of efficiency and accuracy for model development. Working with Snorkel ensures the highest frontier model success rate and creates a true partnership between model developer and data provider.”
Andy Harrison, CEO and General Partner of S32
