Techtalks: Traveltech

I think it's the Stripe API: Stripe offers a comprehensive suite of payment solutions, including medical billing. Their API is easy to integrate and offers powerful features such as subscription management, recurring billing, and refund processing.

This software is also great Adyen: Adyen is a global payment technology company that provides multi-channel payment solutions, including medical billing. They offer a secure, scalable and flexible API that supports multiple payment methods and regions, and provides real-time reporting and analytics tools.