An AWS EMR Developer designs, develops, and deploys large-scale data processing applications using Amazon Web Services Elastic MapReduce. They utilize big data technologies like Hadoop, Hive, Spark, and others to process and analyze data. They're responsible for data ingestion, data transformation, and data modeling tasks. They also manage clusters, debug issues, optimize performance, and ensure data security. AWS EMR Developers must understand cloud computing concepts, have programming skills, and be knowledgeable in distributed systems. They work closely with data scientists and analysts, providing them with clean, reliable data for insights and decision-making.