Following example shows how to export Excel files to HTML by using only the GemBox.Spreadsheet .NET component.

GemBox.Spreadsheet is a C# / VB.NET component that provides a simple and efficient way to read, write, convert, and print native Microsoft Excel (XLSX, XLS) and other spreadsheet (ODS, CSV) formats and various document formats (HTML, PDF, XPS) from .NET applications without the need for Microsoft Excel on either the developer or client machines.
GemBox.Spreadsheet Free is free of charge, while GemBox.Spreadsheet Professional is a commercial version that is licensed per developer.
For more information, see GemBox.Spreadsheet Features or try our examples.

Example loads Excel file (in XLS format) and saves the file as HTML:

C# code:

// Load Excel file from XLS format and save it in HTML format.
ExcelFile.Load("Workbook.xls").Save("Workbook.html");

Visual Basic .NET code:

' Load Excel file from XLS format and save it in HTML format.
ExcelFile.Load("Workbook.xls").Save("Workbook.html")