A FpML (Financial products Markup Language) developer designs, implements, and maintains applications for financial systems using the FpML standard. They work with financial instruments such as derivatives and bonds, translating business requirements into FpML messages for seamless data interchange between systems. They often collaborate with business analysts, developers, and stakeholders to ensure the accurate representation of financial data. Additionally, they conduct testing, troubleshooting, and optimization to ensure system efficiency and integrity. Their work is essential in facilitating electronic dealing and processing of financial instruments, promoting transparency and efficiency in financial markets.