In the domestic IoT domain, data is often collected by phys- ical sensors and actuators embedded in the household and used to provide contextually relevant services to end users. Given that this data is often personal, the EU’s General Data Protection Regulation can implicate IoT app devel- opers, requiring them to adhere to "data protection by de- sign and default" to ensure safeguards that protect a data subject’s rights. Yet the simple-to-use task-oriented de- velopment environments that are commonly used to build domestic IoT apps provide little support for developers to engage with data protection measures. In this paper we present an overview of an IoT development environment that has been designed to help developers engage with data protection at app design time. We describe a data tracking feature, which makes all personal flows in an app explicit at development time and which provides the foun- dation for an additonal set of data protection measures, including personal data disclosure risk assessments, trans- parency of processing and runtime inspection.