A BIML (Business Intelligence Markup Language) developer designs, implements, and manages ETL solutions for data warehousing. They use BIML scripts to automate SQL Server Integration Services (SSIS) package generation, reducing manual coding and improving productivity. They also design data models, troubleshoot and optimize data integration and data transformation processes. They work closely with data analysts and other stakeholders to ensure that the data extraction and reporting meet the business requirements. Furthermore, they are responsible for maintaining documentation and ensuring data quality and integrity. Their role is crucial in enabling data-driven decision making in a business.