# Sam O'Keefe

> Sam O'Keefe is the co-founder and CEO of Flex, the San Francisco fintech often called 'Stripe for HSA/FSA payments.' Flex lets health and wellness brands accept the roughly $150 billion of tax-advantaged health-account money that Americans leave sitting unused every year, turning a confusing benefits process into a one-tap checkout. A two-time Y Combinator founder who previously built fraud and risk software at Unit21 and led startup programs at Google, O'Keefe raised a $15M Series A in September 2025 to make 'pay with HSA/FSA' as ordinary at checkout as PayPal.

- **Role:** Co-Founder & CEO at Flex
- **Organizations:** Flex (withflex), Y Combinator (S23)
- **Nationality:** American
- **Known for:** Co-founded Flex, the 'Stripe for HSA/FSA payments,' in 2023, Raised a $15M Series A in September 2025 (total funding ~$18M), Grew Flex's customer base 5x in a single year

## Career timeline

- **2017-2020** — Led startup programs at Google, including Global Head of Startup Programs for Google Cloud
- **2020-2021** — Worked inside Google's Area 120 startup incubator
- **2021-2022** — Operating Partner at Google's Gradient Ventures
- **2022-2023** — Product Lead at Unit21, building fraud, risk and compliance software for banks and marketplaces
- **2023** — Co-founded Flex with Miguel Toledo; joined Y Combinator's Summer 2023 batch
- **2025** — Raised $15M Series A for Flex, co-led by First Round Capital and Core Innovation Capital

## Achievements

- Co-founded Flex, the 'Stripe for HSA/FSA payments,' in 2023
- Raised a $15M Series A in September 2025 (total funding ~$18M)
- Grew Flex's customer base 5x in a single year
- Signed brands including Therabody, NordicTrack, Balanced Body, Alo Wellness, Omnilux and Dermstore
- Built HSA/FSA checkout into partners like Equinox's membership flow
- Two-time Y Combinator founder

## Latest updates

- **2025-09** — Flex announced a $15M Series A co-led by First Round Capital and Core Innovation Capital, with Cameron Ventures, Rethink Impact, Y Combinator and Liquid 2 participating.
- **2026-02** — Featured on the Fitt Insider podcast discussing making health spend simple and priorities for the year ahead, including a checkout integration with Equinox.

## Links

- Website: https://withflex.com
- LinkedIn: https://www.linkedin.com/in/samokeefe/
- YouTube: https://www.youtube.com/watch?v=uyEw0trNpow

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Profile page: https://yespress.io/sam-okeefe
Published by YesPress — https://yespress.io
Last updated: 2026-07-01