The Karl Fischer method is a classic and highly reliable technique for determining trace moisture content in various substances. The coulometric Karl Fischer method is particularly well-suited for samples with an absolute water content of less than 100 μg. Our coulometric Karl Fischer moisture titrator successfully employs this method; it is ideal for measuring trace moisture and—with appropriate operating procedures—can even accurately determine moisture at the trace level. Built upon a microcontroller-based hardware platform, the JF-5 model integrates our deep understanding of the physical and chemical phenomena involved in the measurement process. It offers rapid analysis, high precision, and a direct LCD readout of results. Users can freely configure various analysis methods, and the instrument supports data printing, fixed-time operation, and automated workflows, making it a highly efficient, fully automated precision analytical instrument.