For older versions, such as Excel 2003, you used to be able to download a compatibility pack from theMicrosoft homepage. However, this download is no longer officially available. The free-to-use Excel Viewer, which was used by many to open the new file format, is also no longer officially provided by the publisher. That means it is no longer possible to open and work with the new format in older versions of Excel.
However, you do not necessarily need to buy a new version of Excel to open XLSX files. There are free-to-usealternatives. Microsoft itself offers a solution through Excel Online which you can use directly in your browser. All you need is a user account. Programs from other publishers can also handle XLSX files. For example, the open source software LibreOffice is compatible with Microsoft’s current file extensions. However, sometimes the content may not match the original exactly, especially in terms of the format.
On the other hand, you can still save a file in the oldXLS format in all new versions of Excel. To do so, use the “Save as” option and select the “Excel 97-2003 Workbook (*.xls)” option under “File type”. This will allow all Excel versions published since 1997 to open the file. However, some functions of the XLSX file may not be available in the XLS file, or the formatting may look slightly different. Therefore, this option is only recommended if you know that the recipient of the file does not have any of the newer Excel versions.