Recently, I needed to be able to parse Excel files and to output Excel files. However, I found that my old code from previous blog posts were now problematic:
https://long2know.com/2016/05/parsing-excel-to-a-list-of-objects/
https://long2know.com/2016/06/create-an-excel-template-from-objects/
Those old implementations used EPPlus which is now a commercial product. I wanted something open source.
More Link