title: Is it possible to append multiple .xls files into a single Excel 2003 worksheet without Office Interop?
body: <p>I have an ASP.NET Web API and need to implement this feature for a future version. Specifically: </p>
  
  <ul>
  <li>Several .xls files will be placed in a temporary folder. They have the same width but different heights, as well as different row and column sizes.</li>
  <li>The files need to be appended into one .xls file</li>
  <li>The final excel cannot have multiple worksheets. </li>
  <li>The Office Interop libraries cannot be used because Office is not installed and cannot be instaled on the deployment environment.</li>
  </ul>
  
  <p>Is there a way to do this without using the office interop libraries as specified, or any paid third party libraries (free third party libraries are more than welcome) ?</p>