The C# XLSX Library

IronXL, The Excel class library for .NET Framework, Core, and Standard, has full support for the XLSX file format, Microsofts most recent iteration of the Excel spreadsheet file format.

We can use C# to read XLS files using IronXL, and indeed import data from them, including live formula updating. IronXL can also be used to create XLSX files or convert old XLS files to XLSX files and vice versa.