A Braintree developer specializes in integrating and managing Braintree, a PayPal service that focuses on mobile and web payment systems for ecommerce companies. Their duties include setting up and customizing payment gateways, ensuring secure transactions, troubleshooting and resolving payment issues. They work closely with APIs and SDKs, tailoring Braintree's functionalities according to the business's needs. They also maintain and update the payment systems, ensuring compliance with financial regulations. Their role involves deep understanding of various programming languages, and they often collaborate with other developers to create seamless user experiences.