As far as I know, there is no nim wrapper for libxlsxwriter. The "Interfacing C and Nim" and "Converting C code to Nim" part on [https://github.com/nim-lang/Nim/wiki/Nim-for-C-programmers](https://github.com/nim-lang/Nim/wiki/Nim-for-C-programmers) may be useful.
As for reading XLS, I found [http://libxls.sourceforge.net](http://libxls.sourceforge.net)/ For commercial products to read/write XLS/XLSX, I found [http://libxl.com](http://libxl.com)/ All the above lib are for C.
