3 ms·

.xlsx is a Microsoft Excel file. I bet you can open it with Google Docs, LibreOffice, or something similar.

• mr__y 7y ago
  You can also change extension to .zip, unzip it and read individual xml files from worksheets/ subdirectory. However, because of the horrible schema in those xml this is probably a really bad idea to go that way. It's way better to use the software that parent mentioned