Open XLSX Online
If you don’t have Office Excel 2007 installed to open xlsx, or if you happen to be in a public accessible computer that doesn’t provide a program to open xlsx file, then you can use Google Docs to open xlsx online. The xlsx file you open within Google Docs may not be able to retain its original format, but it is a good alternative to open xlsx whenever you don’t have access to Excel 2007.
ThinkFree and Zoho Writer can be your alternatives to view xlsx online. Beside the ability to open Excel 2007 spreadsheet, these two free online office suites can also open other Microsoft Office 2007 files like docx and pptx.