Flex for WooCommerce
Flex provides a WooCommerce (opens in a new tab) plugin to make it easy to accept HSA/FSA payments in your WooCommerce store checkout flow.
WooCommerce Checkout Page
When a customer goes to checkout from your WooCommerce store, they'll be able to select "Flex | Pay with HSA/FSA" and then be redirected to a hosted Flex Checkout page.
Hosted Flex Checkout Page
Upon successful completion, the customer will be redirected back to the WooCommerce success order page. The order will appear in your WooCommerce admin just like a regular order.