title: How to open an Excel file (97-2003) that is password protected, without Microsoft Office Interop
body: <p>The software I'm currently working on uses Microsoft Office Interop to read and write Excel files (97-2003). We want to get rid of Microsoft Office Interop because it forces the user to have Office installed and it's very slow.</p>
  <p>Upgrading to the more recent 2007+ format (.xlsx) is not an alternative because the software has to be able to read the .xls files our customers are currently using.</p>
  <p>I've looked into multiple librairies, like NPOI, ExcelLibrary, LibXL, IronXL and more, but none of these seem to be able to open a password protected <strong>workbook</strong>.
  The only way I found to open a protected .xls workbook is with very expensive libraries, and there are not a lot of them. I know the password to open the Excel file.</p>
  <p>Am I missing any ways to open an Excel file (.xls 97-2003) with a password protected workbook?</p>
  <p>EDIT:
  We ended up buying <a href="https://www.tmssoftware.com/site/flexcelnet.asp" rel="nofollow noreferrer">FlexCel for .NET</a>. So far I am satisfied with the product, the price is not so bad and it seems to be working pretty good! It is much faster than Microsoft Office interop.</p>
  <p>I'm still very surprised that I couldn't find a free and open source solution.</p>