An Apache Samza developer designs, develops, and manages large-scale processing systems for real-time data. They work with Apache Samza, a distributed stream processing framework, to process data that flows continuously from various sources. They implement and maintain Samza jobs to efficiently process, analyze, and store data, ensuring high reliability and fault-tolerance. They tune performance, debug issues, and integrate with other systems. Additionally, they collaborate with other teams to understand data requirements and translate them into Samza applications. They also keep up-to-date with the latest advancements in stream processing technologies to improve system performance and capabilities.