Integrate HSA/FSA into any Checkout
Medpaid provides integration with Checkout Champ, a WordPress WooCommerce plugin and an API for custom solutions so your team can ship HSA/FSA payment solutions without building compliance systems from scratch.
API Reference
Full documentation for all public Plugin API endpoints — organized by resource group with request/response schemas.
Browse API →Setup Guides
Step-by-step integration guides for WordPress/WooCommerce and Checkout Champ.
Get Started →Medpaid Reimburse
A pre-built solution that adds post-purchase HSA/FSA reimbursement to any Checkout Champ order confirmation page.
View Solution →Authentication
All Plugin API endpoints use query-parameter authentication. Include your OnboardingKey and ExternalKey on every request. These credentials are issued when your merchant account is created.
- Keep your keys out of client-side code — proxy through your server.
- Keys are scoped to your merchant account and cannot access other merchants.
- Contact support@medpaid.com to rotate or retrieve credentials.
GET https://api.medpaid.com/plugin/clients/get-client
?OnboardingKey=ok_your_key_here
&ExternalKey=ek_your_key_hereNeed credentials? Contact the Medpaid team or email support@medpaid.com.
Three steps to go live.
Get your credentials
Contact Medpaid to receive your OnboardingKey and ExternalKey. These are issued after your merchant account is reviewed.
Configure your platform
Call configure-platform with your store domain, callback URLs, and plugin key to connect Medpaid to your storefront.
Push your first cart
When a shopper selects HSA/FSA at checkout, push the cart to Medpaid and redirect them to the returned CartReference URL.
Ready to integrate?
Browse the full Plugin API reference or jump straight into a setup guide for your platform.