# Alexander Ratner

> Alexander Ratner is the co-founder and CEO of Snorkel AI, the company he spun out of Stanford's AI lab in 2019 after building the Snorkel open-source project during his PhD. A Harvard physics graduate turned Stanford computer scientist, Ratner pioneered the field of data-centric AI and weak supervision - the idea that better data, not just better models, is the key unlock for enterprise AI. Under his leadership, Snorkel AI reached a $1.3 billion valuation in 2025 following a $100 million Series D, with $148M in annual revenue and customers including some of the world's largest enterprises and LLM developers.

- **Role:** Co-Founder and CEO at Snorkel AI
- **Organizations:** Snorkel AI, University of Washington, Stanford University
- **Nationality:** American
- **Education:** Secondary Education, The Lawrenceville School, A.B. in Honors Physics, Harvard University, PhD in Computer Science, Stanford University
- **Known for:** Co-founded Snorkel AI, which reached $1.3 billion valuation in 2025, Pioneered the field of weak supervision and data-centric AI, Led development of Snorkel open-source project, now deployed at Google, Apple, Intel and major government agencies

## Career timeline

- **2007-2011** — Studied Honors Physics at Harvard University
- **2011-2014** — Early career in consulting; wrote scripts to analyze patent databases, fascinated by inaccessible human knowledge encoded in text
- **2014** — Began PhD at Stanford University in Computer Science, advised by Christopher Re
- **2015** — Started the Snorkel open-source project at Stanford AI Lab as an 'afternoon project' with advisor Chris Re
- **2016** — Published Data Programming paper at NeurIPS 2016, establishing weak supervision as a field
- **2018** — Snorkel paper published at VLDB 2018, earning 'Best Of' designation; Snorkel DryBell deployed at Google
- **2019** — Completed Stanford PhD; co-founded Snorkel AI with Christopher Re and others; appointed Affiliate Assistant Professor at University of Washington
- **2021** — Snorkel AI raised $85M Series C at $1B valuation, achieving unicorn status
- **2025-05** — Snorkel AI announced $100M Series D at $1.3B valuation; launched Snorkel Evaluate and Expert Data-as-a-Service products

## Achievements

- Co-founded Snorkel AI, which reached $1.3 billion valuation in 2025
- Pioneered the field of weak supervision and data-centric AI
- Led development of Snorkel open-source project, now deployed at Google, Apple, Intel and major government agencies
- VLDB 2018 'Best Of' award for Snorkel research
- Stanford Bio-X Morgridge Family SIGF Fellowship
- Published landmark NeurIPS 2016 paper on Data Programming
- Grew Snorkel AI to $148M annual revenue with over 700 employees
- Raised $338M total in venture funding including $100M Series D in May 2025
- Appointed Affiliate Assistant Professor at University of Washington's Paul G. Allen School of Computer Science

## Latest updates

- **2025-05** — Snorkel AI announced $100M Series D funding at $1.3B valuation, led by Addition with participation from Prosperity 7 Ventures, Greylock, Lightspeed, BNY, and QBE Ventures.
- **2025-05** — Launched Snorkel Evaluate and Snorkel Expert Data-as-a-Service products, targeting frontier LLM developers and enterprise AI teams.
- **2025** — Snorkel AI reached $148M annual revenue with approximately 776 employees.
- **2024** — Continued building University of Washington affiliation as Assistant Professor in the Paul G. Allen School of Computer Science and Engineering.

## Links

- Website: https://ajratner.github.io/
- LinkedIn: http://www.linkedin.com/in/alexander-ratner-038ba239
- Twitter/X: https://twitter.com/ajratner
- GitHub: https://github.com/ajratner

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Profile page: https://yespress.io/alexander-ratner
Published by YesPress — https://yespress.io
Last updated: 2026-05-13