News
With a $15M Series A, Flex is rewriting the future of health spending — making HSA/FSA payments effortless for everyone, everywhere.
We’ve raised $15M in Series A funding co-led by First Round Capital and CoreVC, with participation from Rethink Impact, and Cameron Ventures. Over the past year, we’ve grown our customer base 5× and now work with household brands like Dermstore, Therabody, Omnilux, and NordicTrack.
September 2, 2025
Sam O'Keefe
Co-founder & CEO of Flex
Overview
Billions of Dollars, Trapped
Overview
Billions of Dollars, Trapped
Overview
Billions of Dollars, Trapped
Billions of Dollars, Trapped
Americans hold nearly $150 billion in Health Savings Accounts (HSA) and Flexible Spending Accounts (FSA) — funds intended to make healthcare more accessible (Devenir). Yet a significant share goes unspent because many consumers aren’t certain what qualifies as an eligible expense, and most retailers don't accept HSA or FSA cards at checkout. Retailers lose out as well: even when selling qualified medical products, they’re often unable to offer HSA/FSA as a payment option.
If you’ve had an HSA/FSA in the past two decades, you’ve experienced the inconvenience of paying out of pocket and filing for reimbursement. And like the average account holder, you may have lost around $450 in unused funds from these accounts at the end of each year.
Flex, Your Partner in Growth
At Flex, our mission is to improve health by making consumer directed spending simple, seamless, and ubiquitous.
Flex works directly with retailers to add HSA/FSA as a method of payment at checkout and raise consumer awareness through merchandising and marketing. Brands using Flex have seen over 50% increase in average order value, checkout page conversion lifts as high as 30%, and a 20% increase in conversion from free trials to paid plans.
Built for Scale, Designed for Simplicity
When HSA/FSA payments are simple and compliant, people can easily access the products and services that support their health, and merchants unlock a predictable and scalable new revenue stream.
Payments that fit your business model – We believe merchants should sell products the way they want. Running multiple subscriptions in a single cart? Managing fulfillment at the product level? We’ve seen and supported it all.
Integrations your way – Whether you want to fully customize with our API or get up and running quickly through our native ecommerce platform integrations, Flex makes it simple to start accepting HSA/FSA payments.
HSA/FSA eligibility done for you – From one product to ten thousand, Flex ensures that retailers and consumers stay fully compliant.
Channel optimization – Flex provides robust reporting and attribution so marketing teams can clearly see the impact of HSA/FSA on their business and maximize ROI from the channel.
HSA/FSA: retail’s next revenue driver
Increasingly consumers are looking outside of traditional healthcare to find solutions. The consumer wellness industry is now at $500B and growing at 5% per year. At the same time, the number of HSA/FSA accounts and contributions are on the rise, and the recent tax bill qualified five million new Americans to open HSA accounts for the first time.
The shift towards consumer driven healthcare isn’t coming, it’s already here. The future of consumer health spending is Flex.
Thank You
Thank you to our customers and partners for trusting us with your checkouts and to the hundreds of thousands of consumers who have purchased through Flex.
To the members of the Flex team who hustle everyday to make it easier for consumers to invest in their health.
To our investors who continue to back our mission: First Round Capital, Core VC, Rethink Impact, Cameron Ventures, Y Combinator, Liquid2, SV Angel, Precursor, and many others.
If you’re a business who wants to accept HSA/FSA at checkout, we would love to talk. If you are excited about building the future of health and wellness payments, we are hiring.
Billions of Dollars, Trapped
Americans hold nearly $150 billion in Health Savings Accounts (HSA) and Flexible Spending Accounts (FSA) — funds intended to make healthcare more accessible (Devenir). Yet a significant share goes unspent because many consumers aren’t certain what qualifies as an eligible expense, and most retailers don't accept HSA or FSA cards at checkout. Retailers lose out as well: even when selling qualified medical products, they’re often unable to offer HSA/FSA as a payment option.
If you’ve had an HSA/FSA in the past two decades, you’ve experienced the inconvenience of paying out of pocket and filing for reimbursement. And like the average account holder, you may have lost around $450 in unused funds from these accounts at the end of each year.
Flex, Your Partner in Growth
At Flex, our mission is to improve health by making consumer directed spending simple, seamless, and ubiquitous.
Flex works directly with retailers to add HSA/FSA as a method of payment at checkout and raise consumer awareness through merchandising and marketing. Brands using Flex have seen over 50% increase in average order value, checkout page conversion lifts as high as 30%, and a 20% increase in conversion from free trials to paid plans.
Built for Scale, Designed for Simplicity
When HSA/FSA payments are simple and compliant, people can easily access the products and services that support their health, and merchants unlock a predictable and scalable new revenue stream.
Payments that fit your business model – We believe merchants should sell products the way they want. Running multiple subscriptions in a single cart? Managing fulfillment at the product level? We’ve seen and supported it all.
Integrations your way – Whether you want to fully customize with our API or get up and running quickly through our native ecommerce platform integrations, Flex makes it simple to start accepting HSA/FSA payments.
HSA/FSA eligibility done for you – From one product to ten thousand, Flex ensures that retailers and consumers stay fully compliant.
Channel optimization – Flex provides robust reporting and attribution so marketing teams can clearly see the impact of HSA/FSA on their business and maximize ROI from the channel.
HSA/FSA: retail’s next revenue driver
Increasingly consumers are looking outside of traditional healthcare to find solutions. The consumer wellness industry is now at $500B and growing at 5% per year. At the same time, the number of HSA/FSA accounts and contributions are on the rise, and the recent tax bill qualified five million new Americans to open HSA accounts for the first time.
The shift towards consumer driven healthcare isn’t coming, it’s already here. The future of consumer health spending is Flex.
Thank You
Thank you to our customers and partners for trusting us with your checkouts and to the hundreds of thousands of consumers who have purchased through Flex.
To the members of the Flex team who hustle everyday to make it easier for consumers to invest in their health.
To our investors who continue to back our mission: First Round Capital, Core VC, Rethink Impact, Cameron Ventures, Y Combinator, Liquid2, SV Angel, Precursor, and many others.
If you’re a business who wants to accept HSA/FSA at checkout, we would love to talk. If you are excited about building the future of health and wellness payments, we are hiring.
Flex is the easiest way for direct to consumer brands and retailers to accept HSA/FSA for their products. From fitness and nutrition, to sleep and mental health, Flex takes a holistic view of healthcare and enables consumers to use their pre-tax money to do the same.