A Jasper iReport developer designs and creates business reports using the JasperReports Library. They extract data from various data sources, design report layouts, and format the visual representation of data. They utilize iReport Designer, a graphical tool, to create complex report templates, including charts, subreports, and crosstabs. They also integrate these reports into software applications, ensuring that data is accurately represented for business analysis. Furthermore, they troubleshoot and optimize reports for performance and readability. Ultimately, they provide businesses with meaningful insights to help in decision-making processes.