Free Excel ReadersGoogle Sheet (App in Google Drive) :- Google Sheet is perfect and standalone alternative and can be used offline with an extension but you have to use it within Google Chrome. This is a perfect alternative of MS Excel but because of a web based app, it can be difficult to get use to it. You can use it offline with a Google Chrome extensions.
Zoho Sheet :- Zoho sheet is and Zoho Office tools are complete alternatives for MS office and MS excel, Zoho has additional feature of cloud sync that makes Zoho sheet more better and connected with inbuilt messaging with colleagues.
Microsoft Excel Viewer :- Microsoft offers a free Excel viewer to let you see, edit and copy data from excel. It only allows read and copy data from excel files and you will need a excel editor tool like MS Excel or some of tools listed here.
Open Office’s Plan Maker :- Open Office is a great MS office alternatives and they are good enough to replace your Paid Microsoft office suite and Plan makers is very much similar to MS Excel in many terms and best thing, it is free.
There are a bunch of free alternative of Microsoft Office suite and you can try them out to save your money.