This article explains what XLSX files are, how to open them, and which programs are able to convert them to other spreadsheet formats like CSV or ODS.

How to Open an XLS File in Excel. XLS files are Excel workbook files created in Excel 97 or Excel 2003. The 2007, 2010 and 2013 versions of the program use the XLSX format by default to save ...

Want to convert an Excel file (XLSX or XLS) to GPX format on Windows 11/10? Checkout a free software and online tool to do that.

If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.