XLKit is a modern C++ wrapper for using the Excel XLL SDK. It is used to write native plug-ins (aka Add-Ins) for Microsoft Excel. This is an open-source project distributed under the Mozilla Public License v2.0.
The requirements for this library are:
It was developed using the Excel 2013 XLL SDK and Boost 1.55 although older versions should work as well. The requirement for Visual Studio 2013 is because it uses C++11 features.
Browse the documentation here.