One data provider wants to develop an Excel add-in, these are the requirements:
1) it can be installed on desktop. It adds one menu and buttons in Ribbon, and it also provides some specific functions (to get real-time data, like Bloomberg function).
2) the add-in should work in Excel 2007, 2010, 2013 and 2016.
The question is which technology should be used to create this add-in. Here are some of my thoughts:
1) JavaScript API for Excel does not fit, because it does not work for Excel 2007, 2010.
2) VSTO. Does anyone know if VSTO add-ins work for Excel 2013 and 2016?; Is it possible to build one VSTO add-in that works for all Excel 2007, 2010, 2013 and 2016?
3) C API for Excel. It seems that C API for Excel is used to build XLLs. Does anyone know if C API for Excel can build menu and buttons?