On MagnumV testers, OpenXLSX, an open-source alternative to Microsoft Excel, was successfully evaluated for applications where reading/writing to an Excel file from a user test program or custom GUI tool is the desired solution. This presentation will demonstrate the basic open/close calls of XLSX, how to build Visual Studio 2019 solution files with CMAKE, and compare its read/write performance to the existing Magnum Microsoft OLE calls for *.xls and *.xlsx files. Magnum users using Visual Studio 2013 or Visual Studio 2019 and interested in using other open source libraries with Magnum systems (zlib/pcre/crypto) will learn how CMAKE is used to create Visual Studio build environments and build *.lib/*.dll libraries for use with Magnum test programs.