Techniques and arrangements for allowing modification of transaction flows, user interfaces (UIs), receipt configuration and control of buyer-facing displays associated with transactions between a payment service, a merchant and a buyer are provided. Payment service payment functionality is exposed by the payment service via one or more application programming interfaces (API)s, software development kits (SDKs), or some other web-based communication technique (e.g., a uniform resource locator). The payment service payment functionality exposed by the payment service allows a merchant to customize one or more steps of a transaction between a user and a merchant. A merchant can use the exposed payment service payment functionality to configure and modify the look and feel and/or the steps within a transaction flow. The merchant can also modify a receipt to include other information from the information that is included in a default receipt.