Bytescout.XLS is a library to add to .NET applications (like Visual Basic.NET, C#, ASP.NET) which lets you create, using code, worksheets for both MS Excel and
OpenOffice, in other words, files with an XLS extension (from Excel), XSLX, ODS or CSV.
At no time do you need either MS Excel or OpenOffice installed for it to work correctly. You can create, using source code (by using the library) all types of cells, columns, ranges, insert texts, generate formulas, give formats (style, fonts, sizes, colours), etc.
Bytescout.XLS also lets you export the resulting worksheet files to HTML.