OpenOffice is a suite of open-source productivity products. Available in more than 100 languages and designed as a free alternative to Microsoft's commercial Office product suite, OpenOffice programs allow users to create documents, spreadsheets, multimedia presentations, graphics and databases. By making use of the Microsoft Office 2007 import filters that come standard with OpenOffice version 3.0 and higher, you can open XLSX files using OpenOffice Calc.
Launch the OpenOffice Calc program.
Click "File" in the top menu bar and select "Open."
Locate the XLSX file you want to open in the resulting dialog box, and then double-click its icon. The Microsoft Office 2007 import filters preinstalled in OpenOffice version 3.0 and higher open the file without any input required from you.